Postal codes used in the United Kingdom,British Overseas Territories andCrown dependencies are known aspostcodes (originally, postal codes).[1] They arealphanumeric (the UK is one of only 11 countries or territories to use alphanumeric codes out of the 160 postcode-using members of the ICU).
Postcodes are essentially a location specific routing instruction. The codes designate 121 geographic postcode areas which are mnemonically named after the area's major post town (such as TR forTRuro) although some are named after smaller towns or regional areas. Each postcode area is subdivided into districts, which in turn are subdivided into sectors. A full postcode identifies a group of addresses (typically around +/- 10) or a major delivery point.
The current postcode system evolved from named postal districts introduced in London in 1857 and gradually in other large cities from the 1860s onwards. Districts in London were then subdivided in 1917, with each allocated a distinct number. This was extended to other cities by 1934. The current system (building on the earlier postal districts) was devised by theGeneral Post Office (Royal Mail)[2] and was adopted nationally in stages between 1959 and 1974.
The system was designed with a single objective, to aid (the now) Royal Mail in mechanised sorting ofmail for delivery. Since its roll-out, changes in business needs and new technology have meant that postcodes are now also used in many differing ways: they serve as aggregation units incensus enumeration; designate destinations in route planning software, and help calculateinsurance premiums.
Royal Mail is statutorily responsible for allocation of all postcodes and it continuously maintains the Postcode Address File (PAF) database, which stores address data for around 29 million addresses. The PAF (and access to its data) is overseen by the independent PAF Advisory Board and Ofcom, which regulates postal and communication services in the UK.
The London post town covers 40% ofGreater London. On inception (in 1857/8), it was divided into ten postal districts: EC (East Central), WC (West Central), N, NE, E, SE, S, SW, W, and NW. The S and NE sectors were later abolished. In 1917, as a wartime measure to improve efficiency, each postal district was subdivided into sub-districts each identified by a number; the area served directly by the district head office was allocated the number 1; the other numbers were allocated alphabetically by delivery office, e.g. N2 East Finchley delivery office, N3 Finchley delivery office, N4 Finsbury Park delivery office etc. Since then these sub-districts have changed little.
Some older road signs in Hackney still show the North East (NE) sector/district.
Following the successful introduction of postal districts in London, the system was extended to other large towns and cities. Liverpool was divided into Eastern, Northern, Southern and Western districts in 1864/65, and Manchester and Salford into eight numbered districts in 1867/68.[3]
In 1917,Dublin—then still part of the United Kingdom—was divided intonumbered postal districts. These continue in use in a modified form byAn Post, the postal service of theRepublic of Ireland. In 1923, Glasgow was divided in a similar way to London, with numbered districts preceded by a letter denoting the compass point (C, W, NW, N, E, S, SW, SE).[3]
In January 1932 the Postmaster General approved the designation of some predominantly urban areas into numbered districts.[3] In November 1934 the Post Office announced the introduction of numbered districts (short postal codes) in "every provincial town in the United Kingdom large enough to justify it". Pamphlets were issued to each householder and business in the chosen ten areas (Birmingham, Brighton/Hove, Bristol, Edinburgh, Glasgow, Leeds/Bradford, Liverpool, Manchester/Salford, Newcastle-upon-Tyne, Sheffield)[4] notifying them of the number of the district in which their premises lay. The pamphlets included a map of the districts, and copies were made available at local head post offices. The public were "particularly invited" to include the district number in the address at the head of letters.[5]
A publicity campaign in the following year encouraged the use of the district numbers. The slogan for the campaign was "For speed and certainty always use a postal district number on your letters and notepaper". A poster was fixed to every pillar box in the affected areas bearing the number of the district and appealing for the public's co-operation. Every post office in the numbered district was also to display this information. Printers of Christmas cards and stationery were requested to always include district numbers in addresses, andelection agents for candidates in the upcominggeneral election were asked to ensure they correctly addressed the 100 million items of mail they were expected to post. Businesses were issued with a free booklet containing maps and listings of the correct district number for every street in the ten areas.[4]
Changes were made in towns which had already created numbered postal districts: e.g. in Liverpool, the four compass point districts were expanded and districts were allocated numbers such asLiverpool 8 forToxteth; a single numbering sequence was shared by Manchester and Salford: letters would be addressed toManchester 1 orSalford 7 (lowest digits, respectively); some Birmingham codes were sub-divided with a letter, such asGreat Barr, Birmingham 22 orBirmingham 22a,[6] as can still be seen on many older street-name signs.
The Post Office experimented with electro-mechanical sorting machines in the late 1950s.[7] These devices presented an envelope to an operator, who would press a button indicating which bin to sort the letter into. Postcodes were suggested to increase the efficiency of this process by removing the need for the sorter to remember the correct sorting for as many places.[8] In January 1959 the Post Office analysed the results of a survey on public attitudes towards the use of postal codes, and committed to choosing a town in which to experiment with codes. The envisaged format for the new post code was a six-character alphanumeric code in two parts, with three letters designating the geographical area and three numbers tidentifying the individual address.[9] On 28 JulyErnest Marples, thePostmaster General, announced thatNorwich had been selected, and that each of the 150,000 private and business addresses would receive a code by October. Norwich was selected as it already had eight automatic mail sorting machines in use.[10] The original Norwich format consisted of "NOR", followed by a space, then a two-digit number (which, unlike the current format, could include a leading zero), and finally a single letter (instead of the two final letters in the current format).[11]
In October 1965,Tony Benn as Postmaster General[12] announced that postal coding was to be extended to the rest of the country in the next few years.[13]
On 1 May 1967 postcodes were next introduced inCroydon. The many postcodes for central Croydon began with "CRO", while those of the surroundingpost towns with CR2, CR3 and CR4. The uniform system of a set of three final characters after the space (such as 0AA, known as the inward code) was adopted. This was to be the beginning of a ten-year plan, costing an estimated £24 million. Within two years it was expected that full coding would be used inAberdeen,Belfast,Brighton,Bristol,Bromley,Cardiff,Coventry,Manchester,Newcastle upon Tyne,Newport,Reading,Sheffield,Southampton and theWestern district of London.[14] By 1967, codes had been introduced to Aberdeen, Southampton, Brighton andDerby.[15] In 1970, codes were introduced to the London Western andNorth Western postal districts.[16] In December 1970, much Christmas mail was postmarked with the message "Remember to use the Postal Code" although codes were used to sort mail in only a handful ofsorting offices.[17]
During 1971, occupants of addresses began to receive notification of their postcode. Asked in the House of Commons about the completion of the coding exercise, theMinister of State for Posts and Telecommunications (whose role superseded that of Postmaster General in 1969),Sir John Eden, stated that it was expected to be completed during 1972.[18] The scheme was finalised in 1974 when Norwich was completely re-coded but the scheme tested in Croydon was sufficiently close to the final design for it to be retained, with CRO standardised as CR0 (district zero) thus removing the need to create a CR1 district.[3]
A quirk remained: the central Newport (Gwent) area was allocated NPT at a similar time to Croydon becoming CRO, and surrounding areas were (as today) allocated NP1–NP8. NPT lasted until the end of 1984 when it was recoded NP9.[19]
Girobank's GIR 0AA was the last UK postcode with a fully alphabetical outward code. That code no longer exists in the Royal Mail's PAF, but was taken over by the bank's current owners,Santander UK.[20]
When the national postcode system was introduced, many existing postal districts were incorporated into it, so that postcodes in Toxteth (Liverpool 8) start with L8. The districts in both Manchester and Salford gained M postcodes, soSalford 7 became M7 and so on (and similarly in Brighton and Hove, both using the prefix BN). The old coding lives on in a small number of street signs with (for example) "Salford 7" at the bottom. In other cases, the district numbers were replaced with unrelated numbers. In Glasgow, as a result of the transposition of the earlier compass point districts to "G" districts (C1 became G1, W1 became G11, N1 became G21, E1 became G31, S1 became G41, SW1 became G51, and so on) many of the available G districts have not been allocated (and to do so would disrupt the geographical consistency of the existing numbered districts). In London (as postally defined), postal districts created and mapped in 1917 remain unchanged today despite Greater London, created in April 1965, covering a much larger administrative area. The London post town covers 40% of Greater London and the remaining 60% of Greater London's area has postcodes referring to 13 other post towns. Additionally, there were too few postcodes available to meet the level of demand of addresses in districts in central London (particularly in the WC and EC areas), so these were subdivided further with the resulting districts numbered with a letter suffix following the number of the predecessor district, so as to retain the familiar codes. The PAF refers to these subdivisions as districts.
Postcodes are alphanumeric, and are (surprisingly) variable in length: ranging from six to eight characters (including a space); and also in format (there are six valid formats for postcodes currently listed in the PAF). Each postcode is divided into two parts separated by a single space: theoutward code and theinward code. Theoutward code comprises thepostcode area followed by thepostcode district. Theinward code comprises thepostcode sector followed by thepostcode unit. The postcode for Falstaff Grove, Warwick is CV34 6EY and its four components are shown below:
| POSTCODE | |||
|---|---|---|---|
| Outward code | Inward code | ||
| Area | District | Sector | Unit |
| CV | 34 | 6 | EY |
The outward code is the first part of the postcode. It is between two and four characters long and must be in one of six formats. It is followed by a single space which separates it from the inward code.
Thepostcode area is part of the outward code. There are 121 UK geographical postcode areas. The postcode area in most cases comprises two alphabetical characters; however there are eight single character postcode areas (five cities: B Birmingham, G Glasgow, L Liverpool, M Manchester, S Sheffield; and three London areas: E London East, N London North, W London West).
Postcodes areas generally do not wholly align with historical county or current local authority boundaries, and can also cross national boundaries. The phenomenon whereby postcodes overlap administrative/national boundaries is known as 'straddling'.[21] Some postcodes straddleEngland's borders withWales andScotland, such as CH1 4QJ[a] and DG14 0TF.[b] This has led toBritish Sky Broadcasting subscribers receiving the wrong BBC and ITV regions[citation needed], and newly licensedradio amateurs being given incorrectcall signs[citation needed].
Postcode areas are, mostly, named after a major town or city (such asNR forNorwich). Some are named after a smaller town (e.g. Southall postcode area isUB afterUxBridge) or a combination of towns (e.g.SM appears to be named afterSutton andMorden, andIG appears to be named afterIlford and BarkinG). A small number are named for the region surrounding the main post town (HS for Stornoway, OuterHebrideS;FY for Blackpool, located in theFYlde region;ME for Rochester, part of theMEdway conurbation;DG for Dumfries,Dumfries &Galloway region;TD for Galashiels,TweedDale;TS for Cleveland,TeesSide;SP for Salisbury, SalisburyPlain;ZE for Lerwick, Shetland, formerly titledZEtland). The mnemonic (for all areas other than London) features various combinations - most commonly, first two letters (CH forCHester); first and last letters (BH forBournemoutH); first and key syllable letters (IV forInVerness).
In the case of London (a Post Town), there is not a single "London" postcode area (such as "LO"); rather there are eight, formerly 10 areas (currently N, E, EC, SE, SW, W, WC and NW) reflecting the preceding system for coding London based on compass points.
In the case of Northern Ireland, the entire province has a single postcode areaBT (named forBelfasT).
Thepostcode district is one digit, two digits or (in some London postcode areas only) a digit followed by a letter. It usually contains one but sometimes two or morepost towns.[23]
As a general rule, postcode districts are numbered consecutively from 1, with the exceptions of:
In most postcode areas, the central part of the post town for which the postcode area is named will have the district number 1 e.g. B1 (central Birmingham). In addition, the postcode "aa1 1AA" was often (though not universally) allocated to the crown or principal post office in the central postcode district.
The allocation of postcode district numbers, in most cases, is from the main post town outward e.g. Halifax which has seven districts numbered consecutively HX1 to HX7. There are a number of different numbering allocations and exceptions to this general approach:
London uniquely uses letters for subdivisions of some of its original postcode districts (E1, N1, W1, WC1, WC2, EC1–EC4, NW1, SE1, SW1) with letters used predominately in three areas: W (W1), WC (WC1 and WC2) and EC (EC1–EC4), these being the most central areas with the densest concentration of addresses. The districts are geographically extremely small. The subdivisions are effectively postcode districts in their own right, and are referred to as such in the PAF. Although these new smaller districts could have been given double digit numbers, consistent with postcode districts outside London (e.g. for WC1 in the range WC10-WC19 and for WC2 in the range WC20-WC29), this was not done. Using double-digit numbering might have encountered resistance due to their "micro-size" and also due to the long-standing use and familiarity of "WC1" etc. which signified in some cases a cultural or wealth status which may have been diluted or lost if re-coded from WC1 to, say, WC15.
Even if London had dropped the initial compass points systems to create a single post code area, at the time of the national post code programme 1959–1974, the challenge of the large number of districts (169) for one post town would have required a bespoke naming and numbering system.
Accordingly, many postcode districts are not physically contiguous, despite the inference from their numbering. Likewise, the centrality of a postcode district within a postcode area cannot be reliably inferred from the postcode alone.
Post towns are not part of the postcode but are an important component of complete post address. Larger post towns may use more than one postcode district, for example Crawley uses RH10 and RH11. In a minority of cases, a single number can cover two or more post towns – for example, the WN8 district includes Wigan and Skelmersdale post towns; and the GL17 district contains five post towns.
The inward code is the part of the postcode after the single space in the middle. It is always three characters long. The inward code assists in the delivery of post within a postal district (examples of inward codes are "0NY", "7GZ", "7HF", or "8JQ"[24]).
The postcode sector is made up of a single digit (the first character of the inward code). Most postcode districts do not use all of the sectors 0–9 in order to allow for the possibility of more sectors being added in the face of new development. When postcodes were initially allocated, neighbouring postcode districts were often assigned to contain the sectors between them, with five sectors being allocated to each district, and thus avoiding duplication of sectors in geographically close districts. For example, across the three postcode districtsBS6-8 (which are next to each other in north westBristol), sectors 1-4 were assigned to BS8, sectors 5-7 were assigned to BS6, and sectors 8, 9 and 0 were assigned to BS7 (more recent changes have resulted in all three of those areas now having a sector 9).[25]
The postcode unit is two characters added to the end of the postcode sector. A postcode unit generally represents a street, part of a street, a single address, a group of properties, a single property, a sub-section of the property, an individual organisation or (for instance, in the case ofDriver and Vehicle Licensing Agency) a subsection of the organisation. The level of discrimination is often based on the amount of mail received by the premises or business.
The format is as follows, whereA signifies a letter and9 a digit:
| Format | Coverage | Example |
|---|---|---|
| AA9 9AA | All postcodes except those listed below | CR2 6XH |
| AA99 9AA | DN55 1PT | |
| A9 9AA | B, E, G, L, M, N, S, W | M1 1AE |
| A99 9AA | B33 8TH | |
| A9A 9AA | London postcodes in districts starting: E1, N1, W1 | W1A 0AX |
| AA9A 9AA | London postcodes in: WC postcode area; districts starting EC1–EC4 and SW1; and districts NW1W, SE1P | EC1A 1BB |
Notes:
A postcode can be validated against a table of all 1.7 million postcodes inCode-Point Open. The full delivery address including postcode can be validated against the PAF[26] constituting most (but not all) addresses in the UK.,[27] by PAF licensed users.
Aregular expression for validating UK postcodes is specified in theBritish Standards document BS 7666.[28]
Postcodes can be individually checked, free of charge, on theRoyal Mail's website.
TheChannel Islands and theIsle of Man established their own postal administrations separate from the UK in 1969. Despite this, they adopted the UK-format postcodes in 1993–94:Guernsey usingGY, the Isle of Man usingIM, andJersey usingJE[29] and administer them consistent with the administration practices of Royal Mail.
The independent jurisdiction ofSark was assigned a unique postcode districtGY10 in 2011 to differentiate it fromAlderney. The CEO of Guernsey Post, Boley Smillie, said "this has been a long time coming" and "... Sark should have had its own identity back then [when postcodes were adopted in 1993]".[30]
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British Overseas Territories are generally responsible for their own postal systems, including postcodes. A number of BOTs have been independently introduced poistcodes:Bermuda has developed itsown postcode system, with unique postcodes for street and PO Box addresses,[31] as have theCayman Islands,[32]Montserrat and theBritish Virgin Islands.[33] Montserrat recently introduced postal codes.[34] A system has been under consideration inGibraltar[35][36][37] for some time, but not yet settled.
The postal code systems introduced independently by BOTs are shown below:
| Postcode | Location |
|---|---|
| AI-2640 | Anguilla[38] |
| KYn-nnnn (ListArchived 7 April 2017 at theWayback Machine) | Cayman Islands |
| MSR-nnnn (List) | Montserrat |
| VG-nnnn (List) | British Virgin Islands |
| aa nn oraa aaList | Bermuda |
For the remaining BOTs (including Gibraltar) postcodes have recently been introduced to address long-standing concerns. Mail was often misdirected and sent to the wrong place, e.g., to St Helena instead ofSt Helens, Merseyside[39] orSt Helens, Isle of Wight;[40] and toEdinburgh instead of Edinburgh,Tristan da Cunha, Many online companies would not accept addresses without a postcode[41] and residents were accordingly being denied access to retail and other services.
Mail from the UK continues to be treated as international, not inland, and sufficient postage must be used.[42]
The introduced postcodes broadly follow the structure of the UK postcode system (in that they contain two parts, each alphanumeric, and the second part in the format9AA, with1ZZ adopted for all BOTs except Gibraltar which adopted1AA). In Gibraltar's case, the UK format has been fully adopted (and effectively creates a new postcode areaGX).
| Postcode | Location |
|---|---|
| ASCN 1ZZ[43] | Ascension Island |
| BBND 1ZZ[44] | British Indian Ocean Territory |
| BIQQ 1ZZ[45] | British Antarctic Territory |
| FIQQ 1ZZ[45] | Falkland Islands |
| GX11 1AA[36] | Gibraltar |
| PCRN 1ZZ[44] | Pitcairn Islands |
| SIQQ 1ZZ[45] | South Georgia and the South Sandwich Islands |
| STHL 1ZZ[43] | Saint Helena |
| TDCU 1ZZ[41] | Tristan da Cunha |
| TKCA 1ZZ[46] | Turks and Caicos Islands |
The four-letter outward codes conflict with the UK's two letter outward codes in some respects:
British Sovereign Base Areas ofAkrotiri and Dhekelia in Cyprus useCypriot postal codes for civilian use. The British military use BFPO addresses.
TheBritish Forces Post Office (BFPO) provides a postal service to HM Forces separate from that provided by Royal Mail in the United Kingdom, with BFPO addresses used for the delivery of mail in the UK and around the world. BFPO codes such as "BFPO 801" serve the same function as postal codes for civilian addresses, with the last line of the address consisting of "BFPO" followed a space and a number of 1 to 4 digits.
For consistency with the format of other UK addresses, in 2012 BFPO and Royal Mail jointly introduced an optional alternative postcode format for BFPO addresses, using the new non-geographic postcode area "BF" and the notionalpost town "BFPO". Each BFPO number is assigned to a postcode in the standard UK format, beginning "BF1". Inward codes are assigned as follows: 0 – Germany, 1 – UK, 2 – Rest of Europe, 3 – Rest of World, 4 – Ships and Naval Parties, 5 – Rest of World, Operations and Exercises, 6 – Rest of World, Operations and Exercises.[47] The database was released commercially in March 2012 as part of the Royal MailPostal Address File (PAF).[48][49] A postcode is not required if the traditional "BFPO nnnn" format is used.
The overwhelming majority of postcodes in the 121 postcode areas are "geographic", and provide routing instructions to a defined set of addresses.
Some postcodes (areas, districts, sectors and specific postcodes) are alternatively or additionally functional rather than purely operational. These are generally termed "non-geographic post codes". Non-geographic codes are used for both sorting/routing and applying specific customer-requested services. Most non-geographic postcodes are listed in the PAF, which indicates the "Out Date" (first issue), Large User recipient, special functions/services and the matching geographical (district/sector) for each non-geographic postcode.
"Non-geographic" postcodes may be allocated only to Large Users (by reason just of the mail volume) and/or for additional purposes, many of which were introduced after, or have significantly evolved since, the introduction of the current post code system. These include: Admail, "bulk mail" or other large volumes (government and business), centralised opening and/or scanning of inward mail, competitions, parcel returns,direct marketing andPO boxes. These postcodes are also referred to as "business service indicator addresses".
Non-geographic postcodes cannot be used for identifying location, estimating distance or route finding in SatNav systems.[50]
As with standard postcodes, non-geographic postcodes may be terminated as the business becomes defunct or services adapted or transferred transferred e.g. Jobcentre (as part of the Department for Work and Pensions) typically had theAA98 orAA99 district in many postcode areas but each office is now allocated a specific postcode in the WV98 and WV99 districts, with the physical mail for each local office delivered to the centralised location, and sorted according to individual office and DWP operational areas, and then subsequently routed to the local office in electronic format.[1]). Some districts are dual purpose (they have both geographic and non-geographic postcodes). Separate sectors will be allocated to geographic addressees and non-geographic addresses.
Non-geographic postcodes include -
ForPO boxes outside London, postcode districts or sectors may be exclusively or jointly allocated for PO Boxes. For example, in the Brighton BN postcode area, BN50-BN52 are allocated to PO Boxes in Brighton, Rottingdean and Hove, or where a separate post town is allocated within a postcode district (e.g. TN2 Taunton for geographic addresses and TN2 Wadham for PO Box addresses). The post toen and sectors are discosed in the PAF.
ForPO boxes in London, postcode districts ending in -P, such as SE1P, are usually allocated to PO Boxes, but other letters letters are also used, and the use of -P is inconsistent, as it has been allocated to geographic addresses, such as SW1P.
ForLarge Users, there appear to be no binding rules publicly available for numbering of non-geographic districts, and therefore can be numbered anywhere in the range 0 to 99, but many such districts are allocated a number higher than the currently existing postcode districts and often in the range 90-99 (several government departments use theAA98 orAA99 district in a number of postcode areas) - retrieved from PAF file,List of postcode areas in the United Kingdom. This is possible in most postcode areas as only a very small number have allocated geographic districts in that number range (B90-B98, BT92-BT94, and M90 seem to be the only geographic districts in this range). However, there are many non-geographic districts numbered outside this range (e.g. American Express has the postcode district BN88; in Glasgow G58 is allocated to National Savings, as part of a mnemonic postcode G58 1SB, though it is located in G43 postcode district).
Some postcodes in the "non-geographic" range 90–99 are in fact geographic, but specific to the institution or entity and not part of the surrounding numbering sequence (and thus quite different from the neighbouring properties): for example,EH99 1SP can be used with GPS mapping to locate and navigate to the Scottish Parliament (which is directly opposite the Palace of Holyroodhouse, EH8 8DX, and across the road from 7/4 Canongate, EH8 8BX).
The postcode district SW1A has many significant recipients that have been allocated distinctive post codes by Royal Mail, including the district's primary code, SW1A 1AA, allocated to Buckingham Palace, and SW1A 2AA, allocated to 10 Downing Street.
There is no non-geographic postcode format or range for Royal Mail facilities and/or Post Offices. Postcodes ending1AA were sometimes allocated to post offices (Crown, main and sub-) such as NR3 1AA for Magdalen Street post office in Norwich. The Royal Mail Head Office is EC1A 1AA. Some are terminated following disposal of former Post Office buildings (e.g. EH1 1AA in Edinburgh).
Postcodes ending nHQ
The lettersHQ for the last two letters may also mean it is most likely a non-geographic postcode allocated to a Large User with additional services.
Postcodes ending nBR
The postcode printed on Business Reply envelopes (which do not require a stamp) often ends with the lettersBR but is not an essential and defining feature not definitive of the BR service.
There is also a special postcode forletters to Santa/Father Christmas,XM4 5HQ[47] which is a semi-mnemonic rendition of XMAS HQ.
Girobank's headquarters inBootle used the non-geographic postcodeGIR 0AA.
Many non-geographic postcodes do not appear on Royal Mail's own online postcode finder tool or their Click and Drop online postage printing tool, which can add to confusion when responding to organisations that use such addresses. Likewise, delivery services or couriers other than Royal Mail may not be able to deliver to such non-physical addresses. The UK government provides for couriers alternative geographic addresses to their BX addresses.[2]
Non-geographic postcode districts have been allocated in 63 of the 121 postcode areas (and also in two of three postcode areas of the Crown Dependencies).
| Postcode Area | Non-geographic districts | Notes |
|---|---|---|
| AB | 99 | |
| B | 99 | |
| BA | 9 | |
| BB | 0, 94 | |
| BD | 97, 98, 99 | |
| BN | 50, 51, 52, 88, 91, 95, 99 | 50-52 for PO Boxes |
| BS | 0, 98, 99 | |
| BT | 58 | |
| CA | 95, 99 | |
| CF | 30, 91, 95, 99 | |
| CH | 25-34, 88, 99 | 25-34 for PO Boxes |
| CM | 92, 98, 99 | |
| CR | 9, 44, 90 | |
| CT | 50 | |
| CW | 98 | |
| DE | 1, 45, 99 | For DE1 and DE45, only sectors 0 and 9 respectively |
| DH | 97, 98, 99 | |
| DL | 98 | |
| DN | 55 | Royal Mail services |
| E | 77, 98 | |
| EC | 1P, 2P, 3P, 4P, 50 | 1P to 4P for PO Boxes |
| EH | 77, 91, 95, 99 | |
| G | 9, 58, 70, 79, 90 | |
| GL | 11 | |
| GU | 95 | |
| HP | 22 | |
| IP | 98 | |
| IV | 99 | |
| KY | 99 | |
| L | 67, 69, 70, 71, 72, 73, 74, 75, 80 | 69 for PO Boxes |
| LE | 21, 41, 55, 87, 94, 95 | |
| LS | 88, 98, 99 | 99 for PO Boxes |
| M | 60, 61, 99 | |
| ME | 99 | |
| MK | 77 | |
| N | 1P, 81 | 1P for PO Boxes |
| NE | 82, 83, 85, 88, 92, 98, 99 | 99 for PO Boxes |
| NG | 70, 80, 90 | |
| NN | 99 | |
| NR | 18, 19, 26, 99 | NR18 appears to be both geographic and non-geographic |
| NW | 1W, 26 | 26 for PO Boxes |
| OL | 16, 95 | |
| PE | 99 | |
| PL | 95 | |
| PO | 24 | |
| PR | 0, 11 | |
| RH | 77 | |
| S | 49, 94, 95, 96, 97, 98, 99 | |
| SA | 48, 72, 80, 99 | |
| SE | 1P | PO Boxes |
| SR | 9, 43 | |
| SS | 1 | Post town Westcliff - PO Boxes |
| SY | 99 | |
| TN | 2 | Post town Wadhurst |
| TQ | 9 | |
| UB | 3, 5, 8, 18 | |
| W | 1A | PO Boxes |
| WA | 55, 88 | |
| WD | 99 | |
| WF | 90 | |
| WR | 11, 78, 99 | WR11 post town Broadway |
| WV | 1, 98, 99 | WV1 post town Willenhall |
| YO | 90 | |
| JE | 1, 4, 5 | JE4 for PO Boxes |
| IM | 86, 87, 99 | Allocated to large users and PO Boxes |
Notes:
Royal Mail has sometimes assigned semi-mnemonic postcodes (sometimes based on the actual geographic postcode district) to high-profile organisations.[51]
More recently, Royal Mail has adverteused limited form of postcode customisation, so to make it unique and personal. A customised Postcode can only be issued in the UK for a brand new development or an organisation that already has a large user Postcode. This form of customisation is limited to the last two characters (letters) of the postcode (the postcode unit).
Prominent examples (for both geographic and special case postcodes) issued from the introduction of the modern postcode scheme, and subsequently, are:
| Postcode | Organisation[52] |
|---|---|
| B11HQ | HSBC UKheadquarters at1 Centenary Square, Birmingham |
| TVLicensing[53] (now changed to DL98 1TL) | |
| BX1 1LT | Lloyds Bank formerly known asLloydsTSB Bank[54]—BX postcode area is non-geographic |
| BX2 1LB | Bank of Scotland (part ofLloydsBanking Group)[55]—BX postcode area is non-geographic |
| BX3 2BB | BarclaysBank[56]—BX postcode area is non-geographic |
| BX47SB | TSB Bank—BX postcode area is non-geographic |
| BX55AT | VAT Central Unit ofHM Revenue and Customs[57] (Roman numeral "VAT" = "5AT")—BX postcode area is non-geographic |
| CF10 1BH | Lloyds Banking Group (formerlyBlackHorse Finance) |
| CF99 1SN | Senedd (Welsh Parliament) |
| CO43SQ | University of Essex (Square3) |
| CV4 8UW | University ofWarwick |
| CV35 0DB | Aston Martin after their sports cars named "DB" |
| DA1 1RT | Dartford F.C. (nicknamed TheDarts) |
| Egg Banking (decommissioned in February 2018, after the closure of the bank[58] ) | |
| DE55 4SW | SlimmingWorld |
| DH98 1BT | BritishTelecom |
| DH99 1NS | NationalSavings certificates administration |
| E14 5HQ | HSBCheadquarters at8 Canada Square, Canary Wharf |
| E14 5JP | JP Morgan (Bank Street) |
| E16 1XL | ExCeL London[59] |
| E20 2AQ | OlympicAquatics Centre |
| E20 2BB | OlympicBasketball Arena |
| E20 2ST | OlympicStadium |
| E20 3BS | OlympicBroadcast Centre |
| E20 3EL | Olympic Velodrome |
| E20 3ET | OlympicEton Manor Tennis Courts |
| E20 3HB | OlympicHandball Arena (now theCopper Box) |
| E20 3HY | OlympicHockey Stadium |
| E98 1SN | TheSun newspaper |
| E98 1ST | TheSundayTimes newspaper |
| E98 1TT | TheTimes newspaper |
| EC2N 2DB | DeutscheBank |
| EC2Y 8HQ | Linklatersheadquarters at OneSilk Street |
| EC4Y 0HQ | Royal Mail Group Ltdheadquarters |
| EC4Y 0JP | JP Morgan (Victoria Embankment) |
| EH12 1HQ | NatWest Groupheadquarters |
| EH99 1SP | ScottishParliament[60] (founded in 1999) |
| G58 1SB | NationalSavingsBank (the district number58 also approximates the outline of the initialsSB) |
| Girobank (nowSantander Corporate Banking) | |
| HA9 0WS | WembleyStadium |
| InlandWaterwaysAssociation (decommissioned when the IWA moved office in April 2023[61]) | |
| IV212LR | TwoLochsRadio |
| L30 4GB | Girobank (alternative geographic postcode) |
| LS98 1FD | FirstDirect bank |
| M50 2BH | BBCBridgeHouse |
| M50 2QH | BBCQuayHouse |
| N1 9GU | TheGuardian newspaper |
| N81 1ER | ElectoralReform Services[50][62] |
| NE1 4ST | St James' ParkStadium,Newcastle United |
| NG80 1EH | ExperianEmbankmentHouse |
| NG80 1LH | ExperianLambertHouse |
| NG80 1RH | ExperianRiverleenHouse |
| NG80 1TH | ExperianTalbotHouse |
| RM11 1QT | Queen'sTheatre, Hornchurch |
| PH1 2SJ | StJohnstone Football Club |
| RoyalBank of Scotland Perth Chief Office (now closed) | |
| S2 4SU | SheffieldUnited Football Club |
| S6 1SW | SheffieldWednesday Football Club |
| S14 7UP | TheWorld Snooker Championships at theCrucible Theatre, Sheffield;[63] 147 UP refers to a maximum lead (from amaximum break) in snooker |
| S70 1GW | TheGlassWorks - retail and leisure centre in Barnsley town centre |
| SA99 | Driver and Vehicle Licensing Agency—All postcodes starting with SA99 are for the DVLA offices in theMorriston area ofSwansea. The final part of the postcode relates to the specific office or department within the DVLA. |
| SE10NE | One America Street, the London headquarters of architectural firm TP Bennett |
| SE1 8UJ | UnionJack Club |
| SM6 0HB | Homebase Limited |
| SN38 1NW | Nationwide Building Society |
| SR5 1SU | Stadium of Light,Sunderland AFC |
| SW1A 0AA | House of Commons (Palace ofWestminster; see below for House of Lords) |
| SW1A 0PW | House of Lords (Palace ofWestminster; see above for House of Commons) |
| SW1A 1AA | Buckingham Palace (the Monarch) |
| SW1A 2AA | 10 Downing Street (the Prime Minister) |
| SW1A 2AB | 11 Downing Street (Chancellor of the Exchequer) |
| SW1H 0TL | Transport forLondon (Windsor House, 50 Victoria Street) |
| SW1P 3EU | European Commission and European Parliament office (EuropeanUnion) |
| SW1W 0DT | TheDailyTelegraph newspaper |
| SW1V 1AP | Apollo Victoria Theatre |
| SW1X 1SP | High Commission ofSingapore, London |
| SW11 7US | Embassy of theUnitedStates, London |
| SW19 5AE | AllEngland Lawn Tennis and Croquet Club (Venue of theWimbledon Championships) |
| TW8 9GS | GlaxoSmithKline |
| W1A 1AA | BBCBroadcasting House (independently notable postcode) |
| The former address ofTheFootballAssociation (decommissioned in February 2010 after they moved location[64]) | |
| W1N 4DJ | BBC Radio 1 (discjockey) |
| W1T 1FB |
Postcodes are used to sort letters to their destination either manually, where sorters use labelled frames, or increasingly with letter-coding systems, where machines assist in sorting.[65] A variation of automated sorting usesoptical character recognition (OCR) to read printed postcodes, best suited to mail that uses a standard layout and addressing format.[66]
A long string of "faced" letters (i.e. turned to allow the address to be read) is presented to a keyboard operator at a coding desk, who types the postcodes onto the envelopes in coloured phosphor dots. The associated machine uses the outward codes in these dots to direct bundles of letters into the correct bags for specific delivery offices. With a machine knowledge of the specific addresses handled by each postal walk at each office, the bundles can be further sorted using the dots of the inward sorting code so that each delivery round receives only its own letters.[24] This feature depends upon whether it is cost effective to second-sort outward letters, and tends to be used only at main sorting offices where high volumes are handled.[67]
When postcodes are incomplete or missing, the operator reads the post town name and inserts a code sufficient for outward sorting to the post town, where others can further direct it. The mail bags of letter bundles are sent by road, air or train, and eventually by road to the delivery office.[67] At the delivery office the mail that is handled manually is inward sorted to the postal walk that will deliver it; it is then "set in", i.e. sorted into the walk order that allows the deliverer the most convenient progress in the round.[24][67] The latter process is now being automated, as the roll-out of walk sequencing machines continues.[68][69]
Integrated Mail Processors (IMPs) read the postcode on the item and translate it into two phosphorus barcodes representing the inward and outward parts of the postcode, which the machines subsequently print and read to sort the mail to the correct outward postcode. Letters may also be sequentially sorted by a Compact Sequence Sorter (CSS) reading the outward postcode in the order that a walking postman/woman will deliver, door to door. On such items the top phosphorous barcode is the inward part of the code, the bottom is the outward.[citation needed]
IMPs can also read RM4SCC items, as used in Cleanmail, a different format to the above.
A newer system of five-digit codes calledMailsort was designed for users who send "a minimum of 4,000 letter-sized items".[70] It encodes the outward part of the postcode in a way that is useful for mail routing, so that a particular range of Mailsort codes goes on a particular plane or lorry. Mailsort users are supplied with a database to allow them to convert from postcodes to Mailsort codes and receive a discount if they deliver mail to the post office split up by Mailsort code. Users providing outgoing mail sorted by postcode receive no such incentive since postcode areas and districts are assigned using permanent mnemonics and do not therefore assist with grouping items together into operationally significant blocks. Walksort[clarification needed] was discontinued in May 2012.
There are approximately 1.7 million postcodes in the United Kingdom, the Channel Islands and the Isle of Man.[71]
As of June 2016, there are 124 postcode areas, 2,987 postcode districts, 11,192 postcode sectors, and 1,500 post towns.[71] As of January 2021[update], 55,540 full postcodes in England and Wales contain only one household.[72] Addresses receiving large volumes of mail are each assigned separate "large user" postcodes. But most postcodes are shared by several neighbouring properties, typically covering about 15 addresses.
There are also significant numbers of discontinued (terminated) codes.[73] Each month some 2,750 postcodes are created and 2,500 terminated.[74]
| Component | Part | Example | Live codes[75] | Terminated codes[76] | Other codes [clarification needed] | Total |
|---|---|---|---|---|---|---|
| Postcode area | Out code | YO | 124 | 0 | 3 | 127 |
| Postcode district | Out code | YO31 | 2,984 | 103 | 4 | 3,087 |
| Postcode sector | In code | YO31 1 | 11,197 | 1,071 | 4 | 12,272 |
| Postcode unit | In code | YO31 1EB | 1,767,416[76] | 876,312 | 4 | 2,643,732 |
| Postcode Addresses | Approx. 29,965,962[77] | |||||
Postcodes are allocated by Royal Mail's Address Management Unit. In general, they cannot be purchased or specified by the recipient. The owner of the property covered by the address has no propriety right in the postcode.
The Address Management Unit ofRoyal Mail maintains an official database of UK postal addresses and postcodes in itsPostcode Address File (PAF), which is made available under licence for a fee regulated byOfcom. The PAF is commercially licensable and is often incorporated in address management software packages. The capabilities of such packages allow most addresses to be constructed solely from the postcode and house number. By including themap references of postcodes in the address database, the postcode can be used to pinpoint a postcode area on a map. PAF is updated daily.
On its website, Royal Mail publishes summary information about major changes to postcode sectors and postal localities (including post towns). Individual postcodes or postal addresses can be found using Royal Mail'sPostcode and Address Finder website, but this is limited to 50 free searches per user per day.
Royal Mail's approach to changing postcodes is formally set out in the PAF Code of Practice, May 2010, agreed between Royal Mail and the Postal Regulator (now Ofcom). Royal mails states that:
"Whenever possible we try not to change addresses and Postcodes. Changes are, however, sometimes necessary to ensure that mail is delivered as quickly and efficiently as possible. For example, occasionally we need to change the way we route mail to provide a better service if a new delivery office is built, and sometimes we run out of Postcodes to allocate to new homes and businesses in a developing area. It is also possible for a local council to prompt a change by re-numbering buildings or re-naming roads.
"In any of the above circumstances, we may need to change existing Postcodes or addresses to ensure that mail is handled efficiently and delivered without delay. If we have to recode as a result of running out of Postcodes for a particular area, Royal Mail will notify addressees of any change following the process set out in Section Three. This process will also be followed when changes are made for other Royal Mail operational or efficiency purposes."[78]
There are several groups, mostly on the fringes of major population centres, who are affected in one way or another by the associations of their postcode. There is a movement in theRoyal Borough of Windsor and Maidenhead to change the first two characters of their postcodes fromSL to WM for vanity, so as not to be associated withSlough.[79] A businessman inIlford wishes to have the postcode district ofIG1 changed toE19 as he claims customers do not realise his business is based in Greater London.[80][importance?]
Some residents of West Heath inSE2 asked to have their postcodes changed to that of adjacentBexleyheath, citing higher insurance premiums as reason to change.[81] Some residents ofKingston Vale inSW15 wish to have their postcodes changed to adjacentKingston upon Thames for the same reasons[citation needed].
In all these casesRoyal Mail has said that there is "virtually no hope" of changing the postcode, referring to their policy of changing postcodes only to match changes in their operations.[82] Under this policy residents of theWirral Peninsula had their postcodes changed from theL (Liverpool) toCH (Chester) group when a new sorting office was opened.[83]
Some postcode areas straddleEngland's borders withWales andScotland. Examples of such postcodes includeCH4,SY10,NP16 andTD15. This has led toBritish Sky Broadcasting subscribers receiving the wrong BBC and ITV regions[citation needed], and newly licensedradio amateurs being given incorrectcall signs[citation needed].
Prior to 1 April 2010, the Royal Mail licensed use of the postcode database for a charge of about £4,000 per year.[84] Following a campaign and a government consultation in 2009,[85] the Ordnance Survey released Code-Point Open, detailing each current postcode in Great Britain together with a geo-code for re-use free of charge under an attribution-only licence (Open Government Licence as part ofOS OpenData).
Under the government'sOS OpenData initiative, it is available for re-use without charge under an attribution-only licence. The Code-Point Open list includes median coordinates for each postcode but excludes postcodes in Northern Ireland and theCrown dependencies. Unlike the PAF products provided by Royal Mail, the Code-Point Open list does not include postal address text.
TheOffice for National Statistics (ONS Geography) also maintains and publishes a series of freely available, downloadable postcode products that link all current and terminated UK postcodes to a range of administrative, health, statistical and other geographies using the Code-Point Open grid reference, under similar licence terms to the OS product. Both the ONSPD and NSPL contain Northern Ireland postcodes, with centroid coordinates in theOSI grid as opposed to theOSGB grid, although Northern Ireland postcodes are subject to a more restrictive licence permitting internal business use only.[86]
Postcodes for the Crown Dependencies are also included, without co-ordinates. A further difference is that non-current postcodes and dates of introduction and withdrawal of postcodes are included.
While postcodes were introduced to expedite the delivery of mail, they are useful tools for other purposes, particularly because codes are very fine-grained and identify just a few addresses. Among these uses are:
The phrase "postcode lottery" refers to the variation in the availability of services by region, though not always because of postcodes.
For these and related reasons, postcodes in some areas have become indicators of social status. Some residents have campaigned to change their postcode to associate themselves with a more desirable area,[88] to disassociate with a poorer area,[89] to reduce insurance premiums or to be associated with an area with a lowercost of living.[90] In all these casesRoyal Mail has said that there is "virtually no hope" of changing the postcode, referring to their policy of changing postcodes only to match changes in their operations.[91]
Straddling refers to the phenomenon of postcodes overlapping administrative (or other geographic) boundaries. This is because postcodes are defined for mail delivery only and take no account of other geographies. However, postcodes are frequently used for referencing data so straddling can create problems when we want to relate postcode-referenced data to higher geographies (for example electoral wards).[dead link]
When the mail reaches its destination delivery office, it is sorted into postmen's walks. Each postman then 'sets in' his mail into the order of his walk. Where the posttown is an MLO, the primary and walk sorting processes may be performed by machine if the mail already bears code marks
We're introducing new machines so postmen and women no longer need to sort most of their delivery manually. They will receive mail in the order of their route, so they can get straight out on delivery.
Terminated postcodes are postcodes that are no longer used for mail delivery. The most frequent reasons for terminations are postcode reorganisations or the demolition/redevelopment of buildings. Terminated postcodes are occasionally re-used by Royal Mail but usually not before an elapsed period of two years. Terminated postcodes are retained in our postcode directories until or unless they are re-used.