Parliamentaryby-elections in theUnited Kingdom occur when aMember of Parliament (MP) vacates aHouse of Commons seat (due toresignation, death, disqualification or expulsion) during the course of a parliament.

Although the history of Parliament is much older, most of these records concern only the period since1945. Earlier exceptional results are listed separately.

Parliaments ofEngland,Scotland,Ireland and the various unions of these Kingdoms had been assembled since the medieval period, though these bodies only gradually evolved to be democratically elected by the populace and records are incomplete. England and Wales had numerous "rotten boroughs" with tiny and tightly controlled electorates until theReform Act 1832. The most recent significant expansions of the electoral franchise were theRepresentation of the People Act 1918 which allowed some women to vote for the first time and greatly expanded the franchise of men, overall more than doubling the size of the electorate, and theRepresentation of the People (Equal Franchise) Act 1928 which expanded the franchise of women to be equal to that of men.

Furthermore, there are various additional factors complicating comparisons between earlier results and modern cases. Among the most significant aspects of historical elections which are no longer present are:

• Frequent interventions and withdrawals of parties in different seats.
• Frequent coalitions between parties, splits within parties and floor-crossing by members.
• Uncontested elections and truces between parties, in particular during both World Wars.
• Generally more significant competition from independent candidates and minor parties.
• Multi-member seats anduniversity seats (abolished 1950).
• Higher frequency of by-elections, partly due to the practice of often uncontestedministerial by-elections which ended in 1926.
• Generally higher turnouts, although several wartime elections exhibited the lowest recorded turnouts.
• Generally higher variation in size of constituency electorates.

Since 1945, the legal and general political situation regarding by-elections has been broadly stable, allowing for meaningful comparison of records.

These records include those fromNorthern Ireland. However, the politics of Northern Ireland is mostly separate from that of Great Britain so comparisons can be problematic.

For comparison purposes the following definitions have been adopted.

• Gain - victory by a party that was not victorious at the immediate previous election
• Loss - defeat of a party that was victorious at the immediate previous election
• Hold - victory by a party that was victorious at the immediate previous election
• Win - victory by a party. ambiguous term that could mean either a gain or a hold
• Incumbent - the party that held the seat at the immediately previous election, irrespective of any intervening change of candidate or candidate's change of party
• Third party - In England, since1922, the "third party" has been theLiberal Party and its successor, theLiberal Democrats. Additionally, inScotland andWales theScottish National Party (SNP) andPlaid Cymru are also considered to be third parties. Prior to 1922, the third party was theLabour Party.
• Minor party - parties smaller than the third party
• Uncontested - an election where only one candidate is put forward. No votes are actually cast and the candidate is by definition the victor.

For more information about what is meant by the term "swing", seeSwing (United Kingdom)

It is rare to see anyswing towards the governing party in by-elections. However, there are some examples of it happening.

*BOLD indicates winning party

A party's share of the vote at a general election is not always matched at subsequent by-elections, but given the five-year maximum term of a Parliament, reductions of 20% or more are unusual. Those of 25% or more are listed below:

In the1934 Merthyr by-election the Independent Labour Party share dropped from 69.4% in the1931 general election to 9.8% (a record 59.6% loss) losing the seat to the Labour Party. However, the 1931 election had no Labour Party candidate, and the MP,R. C. Wallhead, had previously been elected as a Labour candidate in prior elections, when the ILP was affiliated to Labour. Prior to his death, Wallhead joined the Labour Party, so this result could be classed as a Labour hold.

The1919 East Antrim by-election saw theIrish Unionist party face its firstUnionist opposition in the seat since 1906 (in the1918 general election the heavily unionist area gave the Irish Unionist 94.6% of the vote in a contest with a Sinn Féin candidate). AnIndependent Unionist candidate won the seat, with the Irish Unionist share dropping by 52.8%

Worst results for other parties:

Winning shares of the vote above 90%, since 1918:

Majorities over 9,000 votes overturned:

Winning shares of the vote below 35%, since 1918:

The1920 Stockport by-election was held to elect two MPs. The winners' shares of the total vote were 25.6% and 25.1%. However, as each voter could cast two votes, the situation is not readily comparable to other by-elections in this period.

At the1909 Sheffield Attercliffe by-election, the winning candidate took only 27.5% of the vote.

Major parties winning 2% or less share of votes cast in a by-election, since 1918:

The worst Conservative performance was in the1995 North Down by-election, where they took 2.1% of the votes cast.

The 'continuing'Social Democratic Party (SDP) took 0.4% of the vote at both the1990 Upper Bann by-election and theBootle by-election the following week.

Since 1918:^[a]

All majorities of less than 1,000 since the Second World War. Bold entries indicate a new record.

Other very small majorities have been recorded since 1918. The majority in the1921 Penrith and Cockermouth by-election was only 31 votes, and in the1924 Westminster Abbey by-election, it was 43 votes, while at the1928 Carmarthen by-election it was 47 votes.^[2] At the1892 Cirencester by-election, a majority of 3 for the Unionists was overturned on petition, where it was found that both candidates had an equal number of votes. A fresh by-election was called, which was won by the Liberals. The1830 Liverpool by-election saw a majority of 29 votes.^[3]

Turnout is the percentage of registered electors who voted.

The highest turnouts since 1918.

It is highly unusual for a by-election to attract a higher turnout in a seat than the previous general election.

During the Second World War the electoral register was not kept up to date despite significant population movements, especially in the London area (which contains all three constituencies in the first list below). Consequently, only those eligible to vote in the constituency at the outbreak of war were eligible to vote in the by-elections, and many of those were physically unable to vote, as they were located elsewhere; in addition the major parties did not compete against each other. The lowest turnout in peacetime since 1918 was 18.2% at the2012 Manchester Central by-election.^[4] The lowest turnouts since 1918 have been:

• 1942 Poplar South by-election: 8.5%^[2]
• 1941 Harrow by-election: 10.7%
• 1944 Camberwell North by-election: 11.2%

Turnouts of less than 30% since 1945 (bold indicates a new post-war record)

Under current UK electoral law there is no upper or lower limit for candidature numbers, with the only required stipulation being the valid nomination of ten electors from the constituency. By-elections often attract "fringe" or novelty candidates, single-issue candidates, or independents. As with nominations in a general election, candidates must pay a £500deposit, which is only refunded if the candidate wins 5% of the votes cast.

All by-elections with more than ten candidates are listed. Elections are listed in alphabetical order. Those that created a new record number appear in bold.

In 2017, the countermanded poll inManchester Gorton had 11 candidates.

*¹ The most recent mainland UK instance only is given.

*² Four of these eight were between the Unionist incumbent and a "paper candidate" using the name "Peter Barry", the name of the then Irish Minister of Foreign Affairs.

Former Labour cabinet ministerTony Benn contested no fewer than four by-elections during his career, topping the poll on each occasion:Bristol South East in1950,1961 and1963, andChesterfield in 1984. His first and last by-election victories were 33 years and 3 months apart.

Former cabinet minister and European CommissionerRoy Jenkins fought two different by-elections for theSocial Democratic Party only eight months apart. He narrowly failed in the1981 Warrington by-election before winning the1982 Glasgow Hillhead by-election. He had been first elected as a Labour MP almost 34 years previously in the1948 Southwark Central by-election.

FormerSpeaker of the House of Commons,Betty Boothroyd finally secured election at her third by-election attempt at the1973 West Bromwich by-election. She had previously failed in the1957 Leicester South East by-election and the1968 Nelson and Colne by-election as well as the general elections of 1959 and 1970.

John Bickley ofUKIP contested three by-elections (all inGreater Manchester) within two years -Wythenshawe and Sale East in February 2014,Heywood and Middleton in October 2014 andOldham West and Royton in December 2015. He was defeated on each occasion, coming closest in Heywood and Middleton where he lost by less than 700 votes. Bickley also contested Heywood and Middleton at the2015 general election, making a total of four parliamentary elections contested in fewer than 24 months.

Perennial fringe candidates include such personalities asBill Boaks, who ran in 19 by-elections. His highest vote was at the1982 Beaconsfield by-election with 99 votes.Screaming Lord Sutch was for most of his career the leader of theOfficial Monster Raving Loony Party, and competed in 34 by-elections (1 for the National Teenage Party) between 1963 and 1997. His highest vote total was 1,114 at the1994 Rotherham by-election.Lindi St Clair of the Corrective Party contested eleven by-elections without success, her highest total being 216 votes as 'Lady Whiplash' at the1990 Eastbourne by-election. Sutch's successor as leader of the Official Monster Raving Loony Party,Alan "Howling Laud" Hope, has, as of the2023 Uxbridge and South Ruislip by-election, contested twenty-one by-elections.^[6]

Under various ballot paper descriptions, David Bishop of theChurch of the Militant Elvis label stood at seven by-elections, receiving 99 votes at the2012 Corby by-election, an increase over his previous high of 93 at the2011 Feltham and Heston by-election.

On 23 January 1986, Wesley Robert Williamson (who changed his name toPeter Barry) stood infour simultaneous by-elections in Northern Ireland.

Arthur Henderson was distinguished in being successful in no fewer than five by-elections in different seats, inBarnard Castle,Widnes,Newcastle upon Tyne East,Burnley, andClay Cross.

Joseph Gibbins is the only person in modern times to gain the same seat twice in two different by-elections. He triumphed for Labour in the1924 and1935 Liverpool West Toxteth by-elections.

William O'Brien won four by-elections, inMallow in 1883,North East Cork in 1887 and thenCork City in1904 and1914. On these last two occasions, he was re-elected having resigned the seat.

Prime MinisterWinston Churchill contested five by-elections in his long career:

• 1899 Oldham by-election in which he was not elected
• 1908 Manchester North West by-election where he was defeated
• 1908 Dundee by-election where he was elected
• 1917 Dundee by-election where he was re-elected.^[7]
• 1924 Westminster Abbey by-election in which he was unsuccessful

John Wilkes won the1757 Aylesbury by-election, and was then elected in theMiddlesex by-elections of February, March and April 1769, on each occasion being subsequently expelled from the House of Commons.

Notes:

¹ by-election gain lost at the subsequent general election

² by-election gain held at the subsequent general election

• 2024 Rochdale by-election: FormerLabour MP for the seat,Simon Danczuk, standing for theReform UK party, finishes in sixth place.
• 2022 Birmingham Erdington by-election: FormerLabour MP forCoventry South EastDave Nellist stands for theTrade Unionist and Socialist Coalition, coming third with 2.1% of the vote.
• 2021 Batley and Spen by-election: FormerGlasgow Kelvin,Bethnal Green and Bow, andBradford West MPGeorge Galloway, formerly of Labour and thenRespect and now representing theWorkers Party of Britain, wins 21% of the vote.
• 2021 Hartlepool by-election: FormerStockton South MPPaul Williams, the Labour candidate, lost the seat in the party's greatest-ever reverse while in Opposition. Former LabourColne Valley MPThelma Walker also stands as anindependent; and former LabourLancaster and Wyre MPHilton Dawson stands for theNorth East Party. Neither win more than 1% of the vote.
• 2019 Brecon and Radnorshire by-election: Previous incumbentChris Davies runs again after being removed by a recall petition and loses the seat to the Liberal Democrats.
• 2019 Newport West by-election: Former ConservativeTatton MPNeil Hamilton stands for theUK Independence Party, winning 8.6% of the votes.
• 2016 Richmond Park by-election: Incumbent Richmond Park MPZac Goldsmith stands as an independent Conservative to protest against a third runway at Heathrow. He loses to the Liberal Democrats.
• 2008 Haltemprice and Howden by-election: FormerVale of Glamorgan MPWalter Sweeney stands as an independent, winning 1% of the votes.
• 2005 Cheadle by-election:Stephen Day fails to regain for the Conservatives a seat he lost by only 33 votes four years previously.
• 1997 Winchester by-election:Gerald Malone fails to regain the seat for the Conservatives, after losing by only 2 votes six months previously.
• 1993 Christchurch by-election:Robert Hayward loses one of the Conservatives' safest seats to the Liberal Democrats.
• 1990 Eastbourne by-election:Richard Hickmet fails to defend the seat for the Conservatives, after publicly stating that for electors not to support him would be a moral victory for theProvisional Irish Republican Army.
• 1989 Pontypridd by-election:Tom Ellis, former Labour and SDP MP, stands for theSocial and Liberal Democrats, losing his deposit.
• 1986 Fermanagh and South Tyrone by-election:Owen Carron fails to regain the seat for Sinn Féin that he held 1981–83.
• 1986 Newry and Armagh by-election: IncumbentUlster Unionist MPJim Nicholson loses his seat in the only one of the fifteen1986 Northern Ireland by-elections to result in a change.
• 1982 Peckham by-election:Dick Taverne, former Labour and Democratic Labour MP, stands for the SDP, fails to take Labour seat.
• 1982 Gower by-election:Gwynoro Jones, former Labour MP, stands for the SDP, fails to take Labour seat.
• 1982 Beaconsfield by-election:Paul Tyler fails for the Liberals in a by-election held during theFalklands War.
• 1981 Warrington by-election:Roy Jenkins narrowly fails to win for the SDP from Labour in its first parliamentary contest.
• April 1981 Fermanagh and South Tyrone by-election:Harry West fails to regain his old seat againstBobby Sands
• 1978 Hamilton by-election:Margo MacDonald fails to repeat the SNP's 1967 triumph.
• 1978 Ilford North by-election:Thomas Iremonger, who had sat for the seat 1954–74, stands as an independent Conservative, winning a mere 1.5% of the vote.
• 1977 Birmingham Stechford by-election:Terry Davis loses a safe Labour seat.
• 1976 Walsall North by-election:David Winnick loses a safe Labour seat.
• 1971 Liverpool Scotland by-election:Peter Mahon stands as an Independent Labour Anti-Abortion candidate, securing 10.3% of the vote.
• 1969 Brighton Pavilion by-election:Thomas Skeffington-Lodge stands for Labour in a safe Conservative seat, 19 years after losing his seat.
• 1967 Nuneaton by-election: Air Vice-MarshalDonald Bennett stands as a National Party candidate, 22 years after losing his seat as a Liberal MP.
• 1965 Salisbury by-election:Horace Trevor-Cox stands as an independent Conservative, 20 years after losing his seat.
• 1965 Leyton by-election:Patrick Gordon Walker narrowly loses a supposed safe seat.
• 1962 South Dorset by-election:Angus Maude narrowly loses.
• 1960 Bolton East by-election:Frank Byers stands for the Liberals.
• 1956 Hereford by-election:Frank Owen fails to regain for the Liberals the seat he previously sat for 1929–1931.
• 1956 Mid Ulster by-election:Michael O'Neill fails to regain the seat, a year after retiring as its MP.
• 1948 Croydon North by-election: Air Vice-MarshalDonald Bennett stands for the Liberals, losing his deposit, andHarold Nicolson, for Labour, but fail to take a Conservative seat three years after both lost their respective seats.
• 1941 Hornsey by-election,1941 Hampstead by-election and two others:Noel Pemberton Billing fails to take a seat, 20 years after standing down as an independent MP.
• 1924 Westminster Abbey by-election:Winston Churchill narrowly fails to take the seat, as a Constitutionalist.
• 1923 Anglesey by-election:Edward Thomas John failed to defend the seat.
• 1921 Woolwich East by-election:Ramsay MacDonald loses a supposed safe Labour seat.
• 1921 Westminster Abbey by-election:Arnold Lupton failed to take a Conservative seat, coming third, ten years after standing down.
• 1921 Cardiganshire by-election:W. Llewelyn Williams defeated in this race, as anti-Coalition Liberal contesting against a Coalition Liberal, three years after abolition of his previous seat.
• 1920 Dartford by-election:Thomas Edward Wing failed to defend the seat, over a year after losing his previous seat, losing it to Labour.

Until the Re-election of Ministers Acts 1919 and 1926 there were many cases ofmembers having to seek re-election on appointment to ministerial office. In eight instances since 1900 they were unsuccessful:

• 1922 Pontypridd by-electionThomas Arthur Lewis was defeated after being appointed aJunior Lord of the Treasury.
• 1921 Dudley by-election SirArthur Griffith-Boscawen was defeated after being appointedMinister of Agriculture.
• 1914 Ipswich by-electionCharles Masterman was defeated in a subsequent attempt to return to the House of Commons.
• 1914 Bethnal Green South West by-electionCharles Masterman was defeated after being appointedChancellor of the Duchy of Lancaster.
• 1912 Manchester South by-election SirArthur Haworth was defeated after being appointed aJunior Lord of the Treasury.
• 1911 North Ayrshire by-electionAndrew Macbeth Anderson was defeated after being appointedSolicitor General for Scotland.
• 1908 Manchester North West by-electionWinston Churchill was defeated after being appointedPresident of the Board of Trade
• 1905 Brighton by-electionGerald Loder was defeated after being appointedLord Commissioner of the Treasury

Note this list coverscompleted service only; it excludes any current MPs.

Notes

• ¹ died
• ² defeated at next general election
• ³ disqualified (Beattie was never elected. He was awarded the seat on the disqualification of his predecessor, only to be found to be disqualified himself)
• ⁴ retired at next general election (seat abolished by redistribution and failed to secure alternative seat)
• ⁵ retired at next general election due to personal difficulties
• ^a returned to Parliament at a subsequent election
• ^b had served previously as an MP

• Henry Francis Compton, Conservative1905 New Forest by-election 46 days²
• Ronald Bell, Conservative1945 Newport by-election 70 days^2a
• Donald Bennett, Liberal1945 Middlesbrough West by-election 73 days²
• John Dumphreys, Conservative1909 Bermondsey by-election 83 days²
• Seaborne Davies, Liberal1945 Caernarvon Boroughs by-election 91 days²
• Ruth Dalton, Labour1929 Bishop Auckland by-election 92 days³
• Joseph Ormond Andrews, Liberal1905 Barkston Ash by-election 97 days²
• DrRobert McIntyre, SNP1945 Motherwell by-election 104 days²
• George Knox Anderson, Conservative1918 Canterbury by-election 113 days³
• Herbert Evans, Labour1931 Gateshead by-election 121 days¹
• Andrew Clarke, Labour1929 Midlothian and Peebles Northern by-election 121 days^2b
• SirHenry Wilson, UnionistFebruary 1922 North Down by-election 121 days⁵
• Joseph Henderson, Labour1931 Manchester Ardwick by-election 135 days^2a
• Evan Cotton, Liberal1918 Finsbury East by-election 151 days²
• David Hardie, Labour1931 Rutherglen by-election 159 days²
• Lord Arthur Hill, Unionist1907 West Down by-election 193 days^7b
• Oswald Cawley, LiberalJanuary 1918 Prestwich by-election 202 days¹
• Francis Norie-Miller, Liberal National1935 Perth by-election 212 days³
• George Banton, Labour1922 Leicester East by-election 230 days^2a
• William Henry Somervell, Liberal1918 Keighley by-election 232 days²
• Noel Edward Buxton, Liberal1905 Whitby by-election 238 days^2a
• Leslie Orme Wilson, Conservative1922 Portsmouth South by-election 243 days^7b
• Leah Manning, Labour1931 Islington East by-election 250 days^2a
• Frederick William Gibbins, Liberal1910 Mid Glamorgan by-election 253 days³
• C. V. F. Palmer, Independent ConservativeFebruary 1920 The Wrekin by-election 261 days¹
• Maurice Healy, Ind. Nationalist1909 Cork City by-election 262 days^2ab
• John Edward Sutton, Labour1922 Manchester Clayton by-election 270 days^2ab
• James Chuter Ede, Labour1923 Mitcham by-election 278 days^2a
• J. J. Cleary, Labour1935 Liverpool Wavertree by-election 281 days²
• SirWilliam Beveridge, Liberal1944 Berwick-upon-Tweed by-election 282 days²
• W. P. Sidney, Conservative1944 Chelsea by-election 288 days⁴
• SirJohn Reith,NationalFebruary 1940 Southampton by-election 293 days⁶
• W. E. Gibbons, Conservative1944 Bilston by-election 309 days²
• Lord Charles Beresford, Conservative1902 Woolwich by-election 320 days^7ab
• Arthur Henderson, Labour1923 Newcastle-upon-Tyne East by-election 323 days^2ab
• James Henry Hall, Labour1930 Whitechapel and St Georges by-election 328 days^2a
• Thomas Naylor, Labour1921 Southwark South East by-election 336 days^2a

¹ died

² defeated at next general election

³ retired at next general election

⁴ retired at next general election, upon succession to a peerage

⁵ assassinated by IRA

⁶ elevated to the Peerage

⁷ resigned

^a returned to Parliament at a subsequent election

^b had served previously as an MP

• Esmond Harmsworth, elected on 15 November 1919 fromIsle of Thanet aged 21 years 170 days.^[9]
• Youngest woman:Bernadette Devlin, elected on 17 April 1969 fromMid Ulster aged 21 years 359 days.

SeeBaby of the House of Commons

Debuts in Parliament:

• John Benbow was 75 or 76 when he held the1844 Dudley by-election for the Conservatives.
• Hucks Gibbs was 71 when he held theApril 1891 City of London by-election for the Conservatives.
• Philip Manfield was 71 or 72 when he held the1891 Northampton by-election for the Liberals.
• SirRobert Pullar was 79 (less 6 days) when he held the1907 Perth by-election for the Liberals.
• David Cleghorn Hogg was 73 when he gained the1913 Londonderry City by-election for the Liberals.
• Sir Swire Smith was 73 when he held the1915 Keighley by-election for the Liberals.
• William Frederick Hicks Beach was 74 when he held the1916 Tewkesbury by-election for the Conservatives.
• SirGeorge Reid was 70 when he held the1916 St George's, Hanover Square by-election for the Conservatives. He was a former Prime Minister of Australia.
• SirJohn Fleming was 69 or 70 when he held the1917 Aberdeen South by-election for the Liberals.
• George Edwards was almost 70 when he gained the1920 South Norfolk by-election for Labour. He was a former agricultural labourer.
• Henry Bruce Armstrong was almost 77 when he held the1921 Mid Armagh by-election for the Ulster Unionists.
• William Nathaniel Jones was 70 when he held the1928 Carmarthen by-election for the Liberals.
• Francis Norie-Miller was 76 when he gained the1935 Perth by-election for the Liberal Nationals.
• James Little was 70 when he held the1939 Down by-election for the Ulster Unionists.
• John Evans was 70 when he held the1946 Ogmore by-election for Labour.

Comebacks to Parliament:

• John Blaquiere was 71 when he held theJune 1803 Downton by-election for the Tories. He was previously MP forRye in 1801–02.
• Bartholomew Bouverie was 73 when he held the1826 Downton by-election for the Tories. He was previously MP for the same seat from 1819 until thegeneral election earlier in 1826.
• Quintin Dick was 71 when he held the1848 Aylesbury by-election for the Conservatives. He was previously MP forMaldon in 1830–47.
• James William Freshfield was 77 when he won the1851 Boston by-election for the Conservatives. He was previously MP forPenryn and Falmouth in 1835–41.
• William Johnson Fox was 71 when he held the1857 Oldham by-election for the Liberals. He was previously MP for the same seat from 1852 until thegeneral election earlier in 1857.
• William Cubitt was 71 when he held the1862 Andover by-election for the Conservatives. He was previously MP for the same seat in 1847–61.
• John Morgan Cobbett was 71 when he won the1872 Oldham by-election for the Conservatives. He had been previously MP for the same seat as a Liberal in 1852–65.
• James Patrick Mahon was 79 when he held the1879 Clare by-election and 87 when he held the1887 County Carlow by-election for the Irish Nationalists.
• Isaac Holden was 75 when he held the1882 West Riding of Yorkshire by-election for the Liberals. He had previously been MP forKnaresborough in 1865–68.
• Sir Wilfrid Lawson was 74 when he held the1903 Camborne by-election for the Liberals. He had previously been MP forCockermouth in 1886–1900.
• John Frederick Cheetham was 70 when he won the1905 Stalybridge by-election for the Liberals. He had served previously as MP forNorth Derbyshire 1880-85 prior to that seat's abolition.
• Sir Alfred Hopkinson was 74 when he won the1926 Combined English Universities by-election for the Conservatives. He had previously been MP forCricklade 1895-98 before resigning.
• Arthur Salter was 70 when he held the1951 Ormskirk by-election for the Conservatives. He had served previously as MP forOxford University 1937-50 prior to that seat's abolition.

In defence of a previously held seat:

• Enoch Powell was 73 when he successfully defended his seat at the1986 South Down by-election for the Ulster Unionists, after a protest resignation against theAnglo-Irish Agreement, although he had been an MP almost continuously since 1950.

The first woman to be elected in a by-election wasNancy Astor, who succeeded her husband at the1919 Plymouth Sutton by-election, becoming the first woman to take her seat in the House of Commons.

The first woman to gain a seat in a by-election wasSusan Lawrence who won the1926 East Ham North by-election, although she had previously sat for the same seat between 1923 and 1924.¹

The first woman to gain a seatab initio in a by-election wasJennie Lee who won the1929 North Lanarkshire by-election, at the same time becoming the first womanBaby of the House of Commons.

Note¹Mabel Philipson succeeded her husband at the1923 Berwick-upon-Tweed by-election. He had been elected as aNational Liberal Party candidate. She won as aConservative so this could arguably be classed as the first gain by a woman.

Whilst the first ethnic minority Members of Parliament were elected at general elections as early as the 1890s, it would be almost 100 years before one was returned at a by-election.

The first ethnic minority candidate to be elected in a by-election wasAshok Kumar who gained the1991 Langbaurgh by-election for Labour.

• David Lammy held the2000 Tottenham by-election for Labour.
• Mark Hendrick held the2000 Preston by-election for Labour.
• Parmjit Singh Gill gained the2004 Leicester South by-election for the Liberal Democrats.
• Seema Malhotra held the2011 Feltham and Heston by-election for Labour, the first woman to win it.

The first by-election in which all three major-party candidates were from the ethnic minorities was the2007 Ealing Southall by-election, held by Labour.

When the UK Parliament was established in 1801, non-Anglicans were prevented from taking their seats as MPs under theTest Act 1672. However,Methodists took communion at Anglican churches until 1795, and some continued to do so, and manyPresbyterians were prepared to accept Anglican communion, thus ensuring that members of these creeds were represented in the Parliament.^[10] SomeUnitarians were also elected.

The first by-election victor (and first ever MP) to be an adherent of theEastern Orthodox Church wasThe Honourable Frederick North who was elected in 1792 forBanbury (to succeed his brother who had entered the House of Lords), having converted to the faith the previous year.

The firstRoman Catholic by-election victor in the UK Parliament wasDaniel O'Connell in the1828 Clare by-election. He was not permitted to take his seat until the following year.

The firstatheist by-election victor wasCharles Bradlaugh, at the1881 Northampton by-election. As an atheist, Bradlaugh was not allowed to swear theOath of Allegiance, and the by-election was re-run in1882 and1884. Both were also won by Bradlaugh, who eventually was able to take his seat after the1885 general election.^[11]

• David Salomons was the firstJewish by-election victor, at the1851 Greenwich by-election.
• Terry Rooney was the firstMormon by-election victor, at the1990 Bradford North by-election.
• Parmjit Singh Gill became the firstSikh by-election victor, at the2004 Leicester South by-election.
• Virendra Sharma became the firstHindu by-election victor, at the2007 Ealing Southall by-election.
• Rosena Allin-Khan was the firstMuslim by-election victor, at the2016 Tooting by-election.

Most physically disabled MPs in the history of the parliament entered in the intakes of general elections. Those known to have been disabled when entering parliament at by-elections are rarer and include:

• John Horne Tooke, who lost sight of an eye in a boyhood fight, won the1801 Old Sarum by-election.
• Fulk Greville Howard, who lost sight of an eye in theHelder expedition in 1799, won the1808 Castle Rising by-election.
• Sir William Carr Beresford, who lost sight of an eye in an accident on military service in 1786, won the1811 County Waterford by-election.
• Samuel Shepherd, increasingly deaf from 1790, won the1814 Dorchester by-election.
• Arthur MacMurrough Kavanagh, born without hands and feet, won the1866 Wicklow County by-election.
• Michael Davitt, who lost his right arm in a factory accident in 1857, won the1882 Meath by-election, although he was disqualified from sitting because he was in prison.
• Aubrey Herbert, who was almost blind from childhood, won the1911 South Somerset by-election.
• Mabel Philipson, who lost sight in one eye after a car crash in 1911, who won the1923 Berwick-upon-Tweed by-election.^[12][13]
• John Dugdale, who was partly deaf from childhood, won the1941 West Bromwich by-election.
• Violet Bathurst, Lady Apsley, who was left permanently disabled and unable to walk by a hunting accident in 1930, won the1943 Bristol Central by-election,^[14]
• Cecil Manning, who lost his right arm in action inWorld War I, won the1944 Camberwell North by-election.
• Hervey Rhodes, who walked with a limp since severe wounding in World War I, won the1945 Ashton-under-Lyne by-election.
• William Rees-Davies, who lost his right arm in action inWorld War II, won the1953 Isle of Thanet by-election.

• Malcolm St Clair,1961 Bristol South East by-election (resigned in 1963 to enableanother by-election)
• Charles Beattie,1955 Mid Ulster by-election (he too was disqualified a few weeks later, causinganother by-election)
• Pre-1945:Stephen Moore,March 1875 Tipperary by-election (retired in1880)

• 2024 Rochdale by-election
• 2021 Hartlepool by-election¹ (three former MPs)
• 2008 Haltemprice and Howden by-election²
• 1997 Winchester by-election
• 1986 Fermanagh and South Tyrone by-election
• 1982 Beaconsfield by-election
• 1981 Warrington by-election
• 1969 Brighton Pavilion by-election
• 1965 Salisbury by-election
• 1956 Mid Ulster by-election
• 1948 Croydon North by-election
• 1933 Altrincham by-election (three former MPs)
• 1930 Glasgow Shettleston by-election
• 1930 Nottingham Central by-election (three former MPs)
• 1928 Cheltenham by-election

¹ Hilton Dawson, Thelma Walker, and Paul Williams
² Conservative MPs David Davis and Walter Sweeney

The usual causes of by-elections – death or resignation – mean that incumbent MPs are rarely candidates. Typically, this only occurs if an MP deliberately triggers a by-election to get a mandate for a party change, or to bring a particular issue to public attention. More rarely, it can occur if an election result is challenged in court or, since theRecall of MPs Act 2015, an MP chooses to run after a recall petition against them succeeds. Historically, such cases were more common due to ministerial by-elections (see#Re-election of ministers).

Examples since 1945 include:

• 2019 Brecon and Radnorshire by-election –Chris Davies ran again after a recall petition against him succeeded. Davies lost.
• 2016 Richmond Park by-election –Zac Goldsmith resigned and ran as an independent in protest of plans to expandHeathrow Airport. Goldsmith lost.
• 2014 Rochester and Strood by-election –Mark Reckless defected from the Conservatives to UKIP. Reckless won.
• 2014 Clacton by-election –Douglas Carswell defected from the Conservatives to UKIP. Carswell won.
• 2008 Haltemprice and Howden by-election –David Davis resigned to force a by-election in protest of government policy on civil liberties. Davis won.
• 1997 Winchester by-election –Mark Oaten ran again after his previous win at the 1997 general election was declared void. Oaten won.
• 1986 Northern Ireland by-elections – All unionist MPs in Northern Ireland resigned and ran again in protest of theAnglo-Irish Agreement. One,Jim Nicholson, lost.
• 1982 Mitcham and Morden by-election –Bruce Douglas-Mann defected from Labour to the SDP. Douglas-Mann lost.
• 1973 Lincoln by-election –Dick Taverne left Labour and foundedDemocratic Labour. Taverne won.
• 1961 Bristol South East by-election –Tony Benn was disqualified as an MP after inheriting a peerage, which made him ineligible to sit in Commons. Benn ran again in the following by-election and won, but was disqualified. He would go on to win the1963 Bristol South East by-election.
• 1955 Mid Ulster by-election and1956 Mid Ulster by-election.Tom Mitchell ran in both of these despite being disqualified from the House of Commons. He won in 1955, but was disqualified, and lost in 1956.

The years 1998 and 2020 stand as the two in modern British history without any Westminster election. 1992, 1998, 2010 and 2020 are the four full calendar years in history without a single by-election.

• 1941 The Wrekin by-election: 357 days.James Baldwin-Webb was presumed killed as a result of enemy action whenSS City of Benares was torpedoed on 17 September 1940; the writ was moved on 9 September 1941.
• 1941 King's Norton by-election: 327 days.Ronald Cartland was killed in action on 29–30 May 1940. Initially posted missing, his death was not presumed until January 1941. The writ was moved on 22 April 1941.
• 1941 Hitchin by-election: 272 days. SirArnold Wilson was presumed killed in action on 31 May 1940; the writ was moved on 27 February 1941.
• 1969 Newcastle-under-Lyme by-election: 236 days.Stephen Swingler died on 19 February 1969; the writ was moved on 13 October 1969.
• 1969 Swindon by-election: 220 days.Francis Noel-Baker resigned on 7 March 1969; the writ was moved on 13 October 1969.

The longest period without a seat changing hands in a by-election was the five years between the Conservative victories in the1948 Glasgow Camlachie by-election and the1953 Sunderland South by-election.

During the short Parliaments of 1910, 1950-1 and 1974 no seats changed hands in a by-election.

The Liberal Party endured 29 years without a single by-election gain between the1929 Holland with Boston by-election and the1958 Torrington by-election. It did not win a single by-election in the thirteen years between holding the1945 Middlesbrough West by-election and gaining Torrington.

Until the2008 Crewe and Nantwich by-election, the opposition Conservative Party had not gained a seat in almost 26 years, the last being the1982 Mitcham and Morden by-election, which occurred during the unique circumstances of theFalklands War and the sitting Labour MP defecting to the Social Democratic Party and seeking re-election under his new party label. The Conservatives' last gain while in Opposition was 30 years previously at the1978 Ilford North by-election.

Labour's longest lean stretch was almost 18 years, between gaining the1939 Brecon and Radnorshire by-election and the1957 Lewisham North by-election.¹

As of 27 November 2025, the most recent gains for each currently active party were:

Notes¹ The Labour Party were the official opposition in the Parliament elected in 1935, but after the major parties agreed an electoral truce on the outbreak of war in 1939, they did not contest any Conservative or Liberal seats for the remainder of the Parliament, a period of six years, and were members of thewartime coalition government between May 1940 and May 1945.
² Notional gain: incumbent Conservative stood as UKIP. No UKIP candidate has ever defeated an incumbent of a different party
³ The UUP were also declared winners of the1955 Mid Ulster by-election after the Sinn Féin candidate was disqualified, but the UUP candidate was also disqualified shortly after.
⁴ Sinn Féin have not gained a seat at a by-election since 1918. However, theAnti H-Block party, an Irish Republican group that merged into Sinn Féin, gainedFermanagh and South Tyrone in theApril 1981 by-election (44 years, 7 months and 18 days ago).

The Conservatives did not successfully defend a single by-election in the eight years between their holds of the1989 Richmond (Yorks) by-election and the1997 Uxbridge by-election, losing a record 15 consecutive seats where they were the incumbents. By the time of the by-election in Uxbridge, the victor in Richmond,William Hague, had become leader of the Conservative Party.

Labour's worst run was 4 consecutive by-election losses, which has occurred three times since 1945:

• between holding the1976 Newcastle-upon-Tyne Central by-election and the1977 Grimsby by-election.
• between holding the1967 Manchester Gorton by-election and the1968 Sheffield Brightside by-election.
• between holding the1967 Rhondda West by-election and the1967 Manchester Gorton by-election.

Between the1988 Glasgow Govan by-election and the2003 Brent East by-election, Labour successfully defended every seat it held at by-elections, for a total of 30 holds (not countingFalkirk West andWest Bromwich West, represented by a Labour MP turned independent and a Labour speaker respectively and both won by Labour). The span of 14 years, 10 months and 8 days is the longest period without a by-election defeat for either of the two main parties. The Conservatives did not lose a seat between the2000 Romsey by-election and the2012 Corby by-election, a span of 12 years, 6 months and 12 days. However, they only defended 3 seats in that time. In terms of total number, their longest run of by-election holds was 51, between the1945 Chelmsford by-election and the1957 Lewisham North by-election, a span of 11 years, 9 months and 21 days.

Since their formation, the Liberal Democrats have held every Lib Dem seat contested at a by-election, of which there have been 3. Including their predecessor parties, their most recent by-election loss was the1982 Mitcham and Morden by-election, lost by the SDP 43 years, 5 months and 24 days ago. The SDP candidate had however defected from Labour – the last seat lost by either party that had been won at a previous election was the1957 Carmarthen by-election, lost by the Liberals 68 years, 8 months and 30 days ago. Since 1982, the Liberal Democrats and predecessors together have defended 4; since 1957 they have defended 5 seats.

By-elections in seats held by minor and nationalist parties are rare, and so most have never lost a seat. The SNP lost their first seat at the2023 Rutherglen and Hamilton West by-election. The DUP and Plaid Cymru have defended but never lost a seat at a by-election, Sinn Féin have only lost seats by disqualification, and the UUP have never lost more than one seat in a row. No by-election has ever been called in an SDLP held seat.

For a period of 11 years, from the 1997 general election until the2008 Crewe and Nantwich by-election, the principal opposition Conservative Party failed to register a by-election gain against the incumbent Labour Government. This is the longest period of such failure since records began, and more than twice the previous record of the five years it took the then Labour opposition to gain the1957 Lewisham North by-election. Labour did however lose 3 seats to the Liberal Democrats in that period, their first being the2003 Brent East by-election.

The Labour Party, in its period in opposition starting in 2010, did not register a gain for over nine years, between the2012 Corby by-election and the2022 Wakefield by-election. In this period, the Conservative government lost three seats in by-elections where the former Conservative incumbent stood for a different party (2014 Clacton by-election and2014 Rochester and Strood by-election, both lost to UKIP) or as an independent (2016 Richmond Park by-election, lost to the Liberal Democrats). Their first loss in a by-election without a sitting incumbent was to the Liberal Democrats at the2019 Brecon and Radnorshire by-election.

Apart from the brief parliaments of 1910, 1950-1 and 1974, the parliaments of 1951-5 and 1997-2001 are the only occasions when the Government did not lose a by-election.

The largest number of by-elections held on a single day occurred on 23 January 1986 when15 simultaneous contests were held in Northern Ireland. The elections had been engineered by the incumbent Unionist parties as a protest against theAnglo-Irish Agreement of 1985. They intended the results to be interpreted as a referendum on the treaty. The elections were boycotted by the main Nationalist parties except in four seats where they had a reasonable prospect of victory. In the event, theSocial Democratic and Labour Party gained one seat,Newry and Armagh, from theUlster Unionist Party.

Apart from the above example, it is common for UK mainland parties to schedule several by-elections on the same day. Motivations include attempting to divide opponents' resources and getting bad news (expected losses) out of the way. Since 1945, the largest number of simultaneous mainland by-elections has been 6, held on 16 November 1960. On four occasions, 5 by-elections have been held on the same day, most recently on 9 June 1994. Groupings of two or three are very common.

Before November 2012, the last day on which three by-elections had been held was 23 November 2000. In November 2012 there were two such groupings of three (15 November and 29 November). The last time there were six by-elections in one calendar month was in June 1994.

The largest number of by-elections lost on a single day is three, when the Labour party lostActon,Dudley andMeriden on 28 March 1968, all to the Conservatives.

Occasions since 1945 when two seats have fallen are:

• Bootle:May and November 1990.
• Fermanagh and South Tyrone:April andAugust 1981.
• Bristol South East:1961 and1963.
• Mid Ulster:1955 and1956.
• Edinburgh East:1945 and1947.
• Middlesbrough West:1940 and1945.
• Combined Scottish Universities:1936,1938 and1945.
• Berwick-upon-Tweed:1941 and1944.
• Clay Cross:1936 and1944.
• West Derbyshire:1938 and1944.
• Buckingham:1937 and1943.
• Manchester Gorton:1937 and1942.
• Dunbartonshire:1936 and1941.
• Greenock:1936 and1941.
• Doncaster:1938 and1941.
• Southampton:February andNovember 1940.
• Preston:1936 and1940.
• Wandsworth Central:1937 and1940.
• City of London:1938 and1940.
• Combined Scottish Universities:1934 and1935.
• Eastbourne:1932 and1935.
• Twickenham:1932 and1934.
• Portsmouth South:1922 and1923.
• North Down:1921,February andJuly 1922.
• West Down:1921 and1922.
• South Londonderry:1921 and1922.
• Louth:1920 and1921.
• The Wrekin:February andNovember 1920.
• North Londonderry:1919 and1922.
• Prestwich:January andOctober 1918.
• Edinburgh and St Andrews Universities:1916 and1917.
• St George's Hanover Square:1913,1916 and1918.
• City of London:February andJune 1906.
• Oswestry:1901 and1904.
• Southport:1898 and1899.
• City of London:April andJune 1891.
• Buckingham:1889 and1891.
• Ayr Burghs:1888 and1890.
• Northampton:1881,1882 and1884.
• Preston:1881 andFebruary andNovember 1882.
• Bath:May,June andOctober 1873.
• South Shropshire:1866 and1867.
• East Gloucestershire:January andDecember 1854.
• Greenwich:1851 and1852.
• South Nottinghamshire:1848 and1852.
• Buckinghamshire:1837 and1839 and1842 and1845, within two successive parliaments.

• Batley and Spen:2016 and2021
• Hemsworth:1991 and1996.
• Upper Bann:1986 and1990.
• Belfast South:1982 and1986.
• Fermanagh and South Tyrone:August 1981 and1986.
• Nuneaton:1965 and1967.
• Ormskirk:1951 and1953.
• Liverpool Wavertree:1931 and1935.
• Twickenham:1929,1932 and1934.
• Westminster Abbey:1921 and1924.

British Parliamentary elections are invariably held on a Thursday. The last by-election not held on a Thursday was the1978 Hamilton by-election, held on Wednesday 31 May due to aWorld Cup opening match on the Thursday evening.

Due to an administrative oversight, the1973 Manchester Exchange by-election was held on Wednesday 27 June 1973. Prior to that, the last by-elections not held on a Thursday were the1965 Saffron Walden by-election held on Tuesday 23 March, and the1965 Roxburgh, Selkirk and Peebles by-election held the following day.

Until the mid-1960s, it was common to hold by-elections on any day of the week (other than Sunday).

Very occasionally, a scheduled by-election may be overtaken by the calling of a general election and the dissolution of Parliament, in which case the poll is countermanded by the Returning Officer. There have been only three occasions since 1918: a by-election was scheduled to take place inWarwick and Leamington on 21 November 1923, but was cancelled by a dissolution of Parliament on 16 November. A by-election was scheduled to poll between 13 and 17 October 1924 inLondon University but was cancelled by a dissolution of Parliament on 9 October. In 2017 theManchester Gorton by-election was cancelled by a Motion in the House of Commons following the calling of the2017 United Kingdom general election.^[15]

Occasionally seats are left vacant for a substantial period.

No by-election writ was moved for any seat held bySinn Féin after the 1918 general election. Four Sinn Féin candidates were elected in two different seats and would have had to decline one of them if they had wanted to take their seats. They wereÉamon de Valera (East Clare andEast Mayo),Arthur Griffith (East Cavan andNorth West Tyrone),Eoin MacNeill (Londonderry City andNational University of Ireland) andLiam Mellowes (East Galway andNorth Meath).

By the end of the Parliament, the following Sinn Féin MPs had died without being replaced:Pierce McCan (East Tipperary) ofinfluenza on 6 March 1919,Terence MacSwiney (Mid Cork) following a hunger strike inBrixton prison on 25 October 1920,Frank Lawless (North Dublin) as a result of a riding injury on 16 April 1922,Joseph McGuinness (Longford) on 31 May 1922,Cathal Brugha (Waterford) in action during theIrish Civil War on 7 July 1922,Harry Boland (South Roscommon) shot while being arrested on 2 August 1922,Arthur Griffith (East Cavan andNorth West Tyrone) on 12 August 1922, andMichael Collins (South Cork assassinated on 22 August 1922). In each case their seats were abolished in 1922 as a result of the establishment of theIrish Free State.

Other than these cases the longest time a seat has been left vacant with no by-election held is whenDennis Vosper was elevated to the Peerage on 20 April 1964, and no writ was moved by the time Parliament was dissolved on 25 September 1964.

Note

¹Death by hunger strike.

• 1945 Bromley by-election: SirEdward Taswell Campbell died before his election declaration at the 1945 general election.
• 1945 Monmouth by-election:Leslie Pym died before his election declaration at the 1945 general election.
• 1936 Combined Scottish Universities by-election:Noel Skelton died before his election declaration at the 1935 general election.
• 1906 North Galway by-election:Thomas Higgins died before his election declaration at the 1906 general election.

• 2024 Wellingborough by-election:Peter Bone was removed from office byrecall petition following accusations of bullying and sexual misconduct.^[21]
• 2023 Rutherglen and Hamilton West by-election: the seat was declared vacant afterMargaret Ferrier lost a recall petition, after Ferrier was convicted at GlasgowSheriff Court of breaching COVID-19 travel rules in 2020, and suspended from the House of Commons.^[22]
• 2019 Brecon and Radnorshire by-election: the seat was declared vacant afterChris Davies pleaded guilty to filing false expenses claims, and a recall petition was successful.
• 2019 Peterborough by-election: the seat was declared vacant afterFiona Onasanya was convicted of perverting the course of justice in relation to motoring penalty points issued in 2017. This was the first successful recall petition under the provisions of theRecall of MPs Act 2015.

• 2025 Runcorn and Helsby by-election:Mike Amesbury pleaded guilty to assaulting a constituent, the incident being recorded byCCTV camera. He was sentenced to 10 weeks imprisonment, the sentence later suspended on appeal. Amesbury spent three nights in jail. Amesbury's subsequent resignation as an MP prompted a by-election.^[23]
• 2024 Blackpool South by-election:Scott Benton In April 2023 Benton had the whip removed after he had offered to reporters, posing as investors, that he would lobby ministers in return for payments. A parliamentary investigation concluded that he had breached lobbying rules and recommended a 35-day suspension from the House of Commons, triggering a recall petition. Benton's subsequent resignation as an MP prompted a by-election.
• 2023 Tamworth by-election:Chris Pincher resigned, after losing an appeal against suspension from the House of Commons, in the wake of allegations that he had drunkenly groped two men. The Committee for Standards concluded Pincher's "profoundly damaging" behaviour "represented an abuse of power", causing significant damage to Parliament's reputation. Thescandal was also instrumental in the fall of Prime MinisterBoris Johnson.
• 2023 Somerton and Frome by-election:David Warburton resigned in advance of results of investigation into alleged sexual harassment, and his admission to taking cocaine.^[24]
• 2023 Uxbridge and South Ruislip by-election: Former Prime MinisterBoris Johnson resigned 'with immediate effect', in advance of findings of his repeated contempts, and that he deliberately misled Parliament overPartygate, warranting a 90-day suspension.^[25]
• 2022 City of Chester by-election:Chris Matheson resigned after being suspended for serious sexual misconduct.^[26]
• 2022 Tiverton and Honiton by-election:Neil Parish resigned after admitting watching pornography in the House of Commons.
• 2022 Wakefield by-election:Imran Ahmad Khan resigned after his conviction of sexual assault on a 15-year-old boy.
• 2021 North Shropshire by-election:Owen Paterson resigned amid controversy surrounding a report by the Parliamentary Commissioner for Standards which found that he hadbroken paid advocacy rules.
• 2021 Hartlepool by-election:Mike Hill resigned in advance of anemployment tribunal verdict that he had assaulted, harassed and victimised a parliamentary worker.
• 2018 West Tyrone by-election:Barry McElduff resigned after becoming embroiled in a social media controversy.
• 2014 Newark by-election:Patrick Mercer resigned after being suspended from the House of Commons for six months by the Parliamentary Standards Committee for asking parliamentary questions in exchange for money.
• 2013 Eastleigh by-election:Chris Huhne resigned after pleading guilty to perverting the course of justice in relation to persuading his wife to accept motoring penalty points in 2003.
• 2012 Rotherham by-election:Denis MacShane resigned afterHouse of Commons Standards and Privileges Committee recommended he be suspended from the service of the House for twelve months; their inquiry arose from theUnited Kingdom Parliamentary expenses scandal.
• 2011 Barnsley Central by-election:Eric Illsley resigned after pleading guilty to charges of false accounting arising from theUnited Kingdom Parliamentary expenses scandal.
• 2009 Glasgow North East by-election:Michael Martin resigned as Speaker rather than face a vote of no confidence, amid criticism of his actions arising from theUnited Kingdom Parliamentary expenses scandal.
• 2009 Norwich North by-election:Ian Gibson resigned after being debarred as a Labour candidate, due to allegations arising from theUnited Kingdom Parliamentary expenses scandal.
• 1997 Beckenham by-election:Piers Merchant resigned after a newspaper story revealed that his previous denials of an affair were lies.
• 1977 Bournemouth East by-election:John Cordle resigned after he was criticised by a Select Committee for business links to corrupt architectJohn Poulson.
• 1976 Walsall North by-election:John Stonehouse resigned after being convicted of insurance fraud.
• 1973 Berwick-upon-Tweed by-election:Antony Lambton resigned after his visits to prostitutes and use of cannabis were exposed by theNews of the World.
• 1963 Stratford-upon-Avon by-election:John Profumo resigned after his denials of an affair withChristine Keeler were shown to be lies.
• 1959 Harrow East by-election:Ian Harvey resigned after conviction for gross indecency with a guardsman in Hyde Park.
• 1953 Paddington North by-election:Bill Field resigned after conviction for importuning for immoral purposes in a public lavatory.
• 1949 Sowerby by-election:John Belcher resigned after being found to have accepted gifts from businessmen for political favours.
• 1941 Scarborough and Whitby by-election:Sir Paul Latham resigned after he was arrested to be tried by court-martial on 13 charges of disgraceful conduct.
• 1936 Derby by-election:James Henry Thomas resigned after being found to have disclosed budget secrets.
• 1936 Balham and Tooting by-election: SirAlfred Butt resigned after being found to have disclosed budget secrets.
• 1931 Pontypridd by-election:Thomas Mardy Jones resigned after being found to have abused a travel voucher.
• 1926 Buckrose by-election:Guy Gaunt resigned after being cited as co-respondent in a divorce case.

• 1965 Nuneaton by-election: ForFrank Cousins.
• 1965 Leyton by-election: ForPatrick Gordon Walker (defeated).
• 1950 Sheffield Neepsend by-election: ForFrank Soskice.
• February 1940 Southampton by-election: For SirJohn Reith.
• 1940 Wandsworth Central by-election: ForErnest Bevin.
• 1922 Portsmouth South by-election: ForLeslie Orme Wilson.
• February 1906 City of London by-election: ForArthur Balfour.
• 1896 Montrose Burghs by-election: ForJohn Morley.

By-elections are ostensibly to vote for a 'person', not a 'party', meaning that a member switching parties mid-term is not cause for a by-election. However, some members do seek re-election under their new party as a point of principle.

• 2024 Kingswood by-election:Chris Skidmore resigned in opposition to a bill that allows the issuance of new oil and gas licences.
• 2016 Richmond Park by-election:Zac Goldsmith resigned to force a by-election on the issue ofthe expansion of Heathrow Airport, and contested as an Independent. He was defeated bySarah Olney of the Liberal Democrats. Goldsmith later regained his seat the following year at the2017 general election.
• 2008 Haltemprice and Howden by-election:David Davis resigned to force a by-election on the issue of civil liberties. He was re-elected with neither of the other main parties contesting the seat.
• 1986 Northern Ireland by-elections: Fifteen Unionist MPs resigned and re-contested their seats in protest at theAnglo-Irish Agreement. All but one was re-elected.
• 1963 Bristol South East by-election:Malcolm St Clair honoured a pledge to stand down if law changed to allowTony Benn to disclaim his peerage.
• 1938 Kinross-shire and Perthshire by-election: TheDuchess of Atholl resigned in protest atNeville Chamberlain's appeasement policy and sought re-election. She was defeated.
• 1927 Southwark North by-election:Leslie Haden-Guest resigned from the Labour Party over its policy on China, and re-contested the seat as an IndependentConstitutionalist with Conservative support. He was defeated, finishing bottom of the poll. The Liberals gained the seat.
• 1927 Leith by-election:William Wedgwood Benn resigned following his resignation from the Liberal party and joining the Labour Party. He did not contest the by-election out of fairness to the existing Labour candidate. The seat was narrowly held by a new Liberal candidate.
• 1914 Cork City by-election:William O'Brien resigned to submit himself to the voters after theIrish Nationalists had made council gains in Cork. He was returned unopposed.
• 1912 Bow and Bromley by-election:George Lansbury resigned to contest his seat on the issue ofWomen's Suffrage, although he was disenchanted with a range of Labour party policies. He was defeated.
• 1909 Stratford-on-Avon by-election:Thomas Kincaid-Smith resigned from the Liberal Party on the issue of compulsory national service. He stood as an Independent withNational Service League support. He was defeated, finishing bottom of the poll.
• 1906 Mid Cork by-election:D. D. Sheehan resigned and re-contested his seat following his expulsion from the Irish Nationalist group for not signing the party pledge. Re-elected as an independent.

• 1918 East Tyrone by-election:William Redmond resigned in order to defend his late father's seat atWaterford City. He was successful.
• 1914 East Worcestershire by-election:Austen Chamberlain resigned in order to defend his late father's seat atBirmingham West. He was successful.
• 1911 East Wicklow by-election:John Muldoon resigned in order to contest theEast Cork by-election. He was successful.

• 2011 Oldham East and Saddleworth by-election: The result of the2010 general election was declared void because the victor was found guilty of knowingly making false statements about a rival candidate.
• 1997 Winchester by-election: The result of the1997 general election was declared void because ballot papers which had not received the official mark would have affected the result, if counted. Liberal DemocratMark Oaten massively increased the minute majority he had achieved in thegeneral election.
• 1924 Oxford by-election: The result of the1923 general election was declared void because there were irregularities in the election expenses of the successful candidate.
• 1923 Berwick-upon-Tweed by-election: The result of the1922 general election was declared void because there were irregularities in the election expenses of the successful candidate.
• 1911 North Louth by-election: The result of theDecember 1910 general election was declared void because of corrupt practices and bribery on the part of the successful candidate.

• 1961 Bristol South East by-election:Tony Benn had inherited aPeerage from his father. Although by-elections were routinely called where Members had succeeded to the Peerage, the seat was not considered vacated until the Member had received aWrit of Summons to theHouse of Lords, and Benn, who refused to accept the Peerage, did not apply for one. The seat was declared vacant by a resolution of the House of Commons.
• 1956 Mid Ulster by-election:Charles Beattie was found to be disqualified through membership of National Assistance panels. A bill indemnifying him from the consequences of acting as an MP while disqualified was passed by the House of Commons; Beattie did not stand in the by-election.
• 1955 Mid Ulster by-election:Tom Mitchell was disqualified as a felon (resolution of the House).
• 1950 Belfast West by-election: RevJames Godfrey MacManaway was found by theJudicial Committee of the Privy Council to be disqualified, as a minister of theChurch of Ireland.
• 1925 Walsall by-election:William Preston was found to be disqualified owing to his holding government contracts. A bill indemnifying him was passed by the House of Commons and Preston was re-elected at the by-election.
• 1924 Dover by-election:John Astor was disqualified for voting before he took the oath. He was returned unopposed at the by-election.
• 1913 Whitechapel by-election: SirStuart Samuel was found to be disqualified owing to his holding government contracts. A bill indemnifying him was passed by the House of Commons and Samuel was narrowly re-elected at the by-election.
• 1904 City of London by-election:Alban Gibbs was found to be disqualified owing to his holding government contracts. Gibbs resigned and was re-elected unopposed at the by-election.
• 1904 St Albans by-election:Vicary Gibbs was found to be disqualified owing to his holding government contracts. Gibbs resigned and was narrowly defeated at the by-election.

• 1955 South Norfolk by-election:Peter Baker was expelled after being convicted ofuttering forged documents.
• 1947 Gravesend by-election:Garry Allighan was expelled after being found to be in extreme contempt of the House by his peers after selling details of private parliamentary meetings to theEvening Standard.
• 1922 Hackney South by-election:Horatio Bottomley was expelled after being convicted of fraud, perjury and false accounting.
• 1903 Galway Borough by-election: the seat was declared vacant afterArthur Alfred Lynch was convicted of high treason after fighting on the Boer side in theSecond Boer War.

• 1916 Colne Valley by-election:Charles Leach was adjudged a lunatic and his seat declared vacant.

• 1928 Ashton-under-Lyne by-election:Cornelius Homan lost his seat after being declared bankrupt.
• 1922 Camberwell North by-election:Henry Newton Knights lost his seat after being declared bankrupt.
• 1914 North Galway by-election:Richard Hazleton resigned before being declared bankrupt. He discharged his bankruptcy and was returned in the by-election.
• 1912 Hackney South by-election:Horatio Bottomley resigned after filing a bankruptcy petition.
• 1909 South Kilkenny by-election:Nicholas Joseph Murphy was declared bankrupt.

• 1916 Widnes by-election:William Hall Walker resigned to permit him to donate his thoroughbred racing stock to create a National Stud in an "arms-length" transaction. He was returned unopposed at the by-election.

• 1945 Chelmsford by-election:John Macnamara was killed in action fighting in Italy.
• 1944 Berwick-upon-Tweed by-election:George Charles Grey was killed in action fighting in Normandy, France.
• 1944 Bury St Edmunds by-election:Frank Heilgers was killed in a train crash in Ilford.
• 1943 Acton by-election:Hubert Duggan died of tuberculosis contracted on active service.^a
• 1943 Darwen by-election:Stuart Russell died of fever on active service in Egypt.
• 1943 Chippenham by-election:Victor Cazalet was killed in a plane crash in Gibraltar while escorting General Sikorski.
• 1943 Birmingham Aston by-election:Edward Orlando Kellett was killed in action fighting in North Africa.
• 1943 Buckingham by-election:John Whiteley was killed in a plane crash in Gibraltar while escorting General Sikorski.
• 1943 Bristol Central by-election:Lord Apsley was killed in action in a plane crash in the Middle-East.
• 1943 King's Lynn by-election:Somerset Maxwell died of wounds received at the Battle of El Alamein.
• 1942 Salisbury by-election:James Despencer-Robertson died suddenly, apparently from overwork as military secretary at Southern Command Headquarters.^b
• 1942 Llandaff and Barry by-election:Patrick Munro died while taking part in an exercise for the Home Guard at Westminster.
• 1941 The Wrekin by-election:James Baldwin-Webb drowned when the SSCity of Benares was torpedoed.
• 1941 Dudley by-election:Dudley Joel was killed in action while serving with the Royal Navy.
• 1941 Bodmin by-election:John Rathbone was killed in action on bombing operations over Germany.
• 1941 Hitchin by-election: SirArnold Wilson was killed in action over northern France while a gunner in Bomber Command
• 1941 King's Norton by-election:Ronald Cartland was killed in action during the retreat to Dunkirk.
• 1940 Manchester Exchange by-election:Peter Eckersley was killed in action in a plane crash while serving with the Fleet Air Arm.
• 1940 Heywood and Radcliffe by-election:Richard Porritt was killed in action fighting in Belgium.
• 1939 Wells by-election:Anthony Muirhead committed suicide owing to his fear that a leg-injury might prevent his service in the War.^b

Notes: The above list is of those members either mentioned as having died on War Service in a written Commons answer from Prime MinisterWinston Churchill on 19 January 1945, or who appear in theHouse of Commons Book of Remembrance unveiled in 1949.

^a Mentioned in the written Commons answer, but does not appear in theHouse of Commons Book of Remembrance.

^b Not mentioned in the written Commons answer, but does appear in theHouse of Commons Book of Remembrance.

NB: The above list does not include the names of three members whose deaths on active service were overtaken by the 1945 general election. For a complete list seeRecords of members of parliament of the United Kingdom#Second World War

• October 1918 Prestwich by-election:Oswald Cawley had been killed in action in France.
• 1918 Bath by-election:Lord Alexander Thynne had been killed in action in France.
• 1918 Canterbury by-election:Francis Bennett-Goldney had been killed by an on-duty car accident in France.
• 1918 Ross by-election:Percy Clive had been killed in action in France.
• 1918 Manchester South by-election:Philip Glazebrook had been killed in action in Palestine.
• 1917 Wisbech by-election: The HonNeil Primrose died of wounds received in Palestine.
• 1917 Spalding by-election: The HonFrancis McLaren had been killed in a flying accident serving with theRoyal Flying Corps.
• 1917 East Clare by-election:Willie Redmond had been killed in action in Belgium.
• 1917 Henley by-election:Valentine Fleming had been killed by shell fire in France.
• 1916 North Ayrshire by-election:Duncan Frederick Campbell had died in England of wounds received from a landmine on the Western Front.
• 1916 Winchester by-election: The HonGuy Baring had been killed in theBattle of the Somme in France.
• 1916 Tewkesbury by-election:Michael Hicks Beach, Viscount Quenington had died of wounds in Egypt.
• 1915 St Austell by-election: The HonThomas Agar-Robartes had died of wounds received in theBattle of Loos in France.
• 1915 Cardiff by-election:Lord Ninian Crichton-Stuart had been killed in action in France.
• 1915 Uxbridge by-election: The HonCharles Thomas Mills had been killed in action in France.
• 1915 Heywood by-election:Harold Thomas Cawley had been killed in action in theBattle of Gallipoli.
• 1915 Kilmarnock Burghs by-election:William Glynne Charles Gladstone had been killed in action in France.
• 1915 Mid Antrim by-election: The HonArthur O'Neill had been killed in action in theYpres Salient in Belgium.

This list isincomplete; you can help byadding missing items.(August 2008)

• 2024 Rochdale by-election:¹ Labour candidate, loss to Workers Party of Britain candidate.

• 1995 Littleborough and Saddleworth by-election Conservative loss, gained by the Liberal Democrats
• 1995 Perth and Kinross by-election Conservative loss, gained by the SNP
• 1994 Eastleigh by-election Conservative loss, gained by the Liberal Democrats
• 1985 Brecon and Radnor by-election Conservative loss, gained by the Liberals
• 1982 Mitcham and Morden by-election² Labour loss, gained by the Conservatives
• 1958 Rochdale by-election Conservative loss, gained by Labour
• 1934 Merthyr by-election ILP loss, gained by Labour
• 1929 Holland with Boston by-election Conservative loss, gained by the Liberals
• 1927 Bosworth by-election Conservative loss, gained by the Liberals
• 1926 Kingston upon Hull Central by-election³ Liberal loss, gained by Labour
• 1920 South Norfolk by-election Liberal loss, gained by Labour

¹ Labour candidate Azhar Ali was suspended at the time of the election, due to allegedly anti-Semitic comments.

²Bruce Douglas-Mann had been re-elected as Labour MP for the seat in the 1979 general election. In 1981, along with several other MPs, he defected to the newly formedSocial Democratic Party. Against his new colleagues' advice, he honoured a pledge to face his electors under his new party colours and precipitated a by-election. He came second in the by-election which was won by the Conservatives. The new Labour candidate finished third.

³ the Liberal MP, Lt-Commander the Hon.Joseph Montague Kenworthy, defected to Labour and sought re-election under his new colours. He was successful, and the new Liberal candidate lost his deposit.

These records show the rare occasions when the government won a seat they had not won at the previous general election.

¹ Seat awarded by Election Court to Conservative runner-up because Labour victor deemed ineligible.

² An arguable gain; Stockport was a two-member seat; in the 1918 general election it was won by two supporters of the Coalition Government, one a Liberal and one a Labour member. After a death and a resignation, a by-election was held for both seats. The seats were again won by two Coalition Government supporters, but this time a Conservative and a Liberal, while a Labour candidate who did not support the government was unsuccessful.

³ National Liberal elected in 1922 election had his election declared void (electoral fraud). Resulting by-election was a gain for the Conservatives.

⁴ Uncontested gain fromIrish Nationalist.

⁵ Liberal MP defected to Labour and was re-elected as Labour at a by-election the Liberals did not contest.

^aLabour won both the2000 West Bromwich West by-election and2009 Glasgow North East by-election, regarded as a gain from the contest at the United Kingdom general elections in 1997 and 2005 respectively as those seats had been contested by the then Speakers of the House of Commons. Prior to assuming the Speakership they had both been elected as Labour MPs.

^bThe Conservatives were in Coalition government, led by the Liberal Prime Minister,David Lloyd George.

These records show the rare occasions when the official Opposition failed to hold on to a seat they had won at the previous General election.