Until 1885, it was aparliamentary borough, returning twoMembers of Parliament (MPs) until 1832 and only one from 1832 to 1885. The parliamentary borough was abolished in 1885, when the name was transferred to acounty constituency returning one MP. Elections used thebloc vote system when two MPs were returned, and thefirst-past-the-post system of election when one seat was contested.
Westbury returned aConservative Member at every election after 1924.
1885–1918: The Sessional Divisions of Bradford-on-Avon, Melksham, Trowbridge, Westbury, and Whorwellsdon, and part of the Sessional Division of Warminster.
1918–1950: The Urban Districts of Bradford-on-Avon, Melksham, Trowbridge, Warminster, and Westbury, and the Rural Districts of Bradford-on-Avon, Melksham, Mere, Warminster, and Westbury and Whorwellsdown.
1950–1974: The Urban Districts of Bradford-on-Avon, Melksham, Trowbridge, Warminster, and Westbury, and the Rural Districts of Bradford-on-Avon and Melksham, Mere and Tisbury, and Warminster and Westbury.
1974–1983: As prior but with redrawn boundaries.
1983–1997: The District of West Wiltshire, and the District of Salisbury wards of Knoyle, Mere, and Western.
1997–2010: The District of West Wiltshire wards of Adcroft, Bradford-on-Avon North, Bradford-on-Avon South, college, Corsley, Dilton Marsh, Drynham, Ethandune, Holt, John O'Gaunt, Manor Vale, Mid Wylye Valley, Park, Paxcroft, Shearwater, Summerham, Warminster East, Warminster West, Weavers, Westbrook, Westbury with Storridge, and Wylye Valley, and the District of Salisbury wards of Knoyle, Mere, and Western.
Following a review of parliamentary representation in Wiltshire, theBoundary Commission for England created two new constituencies in the county.Chippenham was created mostly from the adjoiningNorth Wiltshire constituency, plus the town ofBradford-on-Avon at the northern end of the Westbury constituency, while the rest of Westbury saw minor changes to its composition and was renamedSouth West Wiltshire. These changes were approved in 2005, to take effect at the following general election, which ultimately took place in 2010.
Another General Election was required to take place before the end of 1915. The political parties had been making preparations for an election to take place and by July 1914, the following candidates had been selected;
Another General Election was required to take place before the end of 1940. The political parties had been making preparations for an election to take place and by the Autumn of 1939, the following candidates had been selected;
^Wilfrid Prest, ‘Ley, James, first earl of Marlborough (1550–1629)’,Oxford Dictionary of National Biography, Oxford University Press, Sept 2004|| online edn, Jan 2008[1], accessed 22 Jan 2009.
^abAt the1722 general election,James Bertie was also elected forMiddlesex, which he chose to represent, and never sat for Westbury. A by-election for his seat was held in March 1723
