The Parliament of the United Kingdom currently has 650 parliamentary constituencies across the constituent countries (England, Scotland, Wales and Northern Ireland), each electing a single member of parliament (MP) to the House of Commons by the plurality (first past the post) voting system, ordinarily every five years. Voting last took place in all 650 of those constituencies at the United Kingdom general election on 12 December 2019.
The number of seats rose from 646 to 650 at the 2005 general election after proposals made by the boundary commissions for England, Wales and Northern Ireland were adopted through statutory instruments. Constituencies in Scotland remained unchanged, as the Boundary Commission for Scotland had completed a review just before the 2005 general election.
Primary legislation provides for the independence of the boundary commissions for each of the four parts of the UK; the number of seats for each of the countries; permissible factors to use in departing from any old boundaries; and a strong duty to consult. For the 2013 review this was primarily the Parliamentary Voting System and Constituencies Act 2011. The Sainte-Laguë formula method is used to form groups of seats split between the four parts of the United Kingdom and the English regions (as defined by the NUTS 1 statistical regions of England).
The table below gives the number of eligible voters broken down by constituent country, including the average constituency size in each country.
|Total electorate for each constituent country|
|Average electorate per constituency for each constituent country|
|Overall UK average||68,184||—||70,547||—||71,314||—||70,997||—||73,181||—|
The constituencies vary considerably in size. The one with the greatest geographical area is Ross, Skye and Lochaber, at about 12,000 square kilometres (4,600 sq mi). The largest in Wales is Brecon and Radnorshire. The smallest constituency by area is Islington North at 7.35 square kilometres (2.84 sq mi).
Parliamentary constituencies in the United Kingdom
The "Region" of the table refers to the NUTS 1 statistical region of England, which coincides with the former European Parliament constituency that the constituency was situated in until 31 January 2020.
As of the 2019 election there are 533 constituencies in England, 40 in Wales, 59 in Scotland and 18 in Northern Ireland.
|Belfast East||66,245||Belfast; Castlereagh|
|Belfast North||72,225||Belfast; Newtownabbey|
|Belfast South||69,984||Belfast; Castlereagh|
|Belfast West||65,644||Belfast; Lisburn|
|East Antrim||64,830||Carrickfergus; Larne; Moyle|
|East Londonderry||69,246||Coleraine; Londonderry/Derry|
|Fermanagh and South Tyrone||72,848||Fermanagh; Dungannon and South Tyrone|
|Lagan Valley||75,735||Lisburn; Banbridge|
|Mid Ulster||70,449||Magherafelt; Cookstown; Dungannon and South Tyrone|
|Newry and Armagh||81,226||Armagh; Newry and Mourne|
|North Antrim||77,134||Ballymena; Ballymoney; Moyle|
|North Down||67,099||Ards; North Down|
|South Antrim||71,711||Antrim; Newtownabbey; Lisburn|
|South Down||79,175||Down; Newry and Mourne; Banbridge|
|Strangford||66,928||Ards; Castlereagh; Down|
|Upper Bann||82,887||Craigavon; Banbridge|
|West Tyrone||66,259||Omagh; Strabane|
Summary of main boundary changes for the 2010 general election
- Scotland – No changes from 2005 election.
- Wales – Number of seats unchanged: three seats were abolished and three were created: Aberconwy, Arfon, and Dwyfor Meirionnydd.
- Northern Ireland – No extra or fewer seats allocated.
- Hampshire, Warwickshire, Derbyshire, Norfolk, Essex, Lancashire, Northamptonshire, Wiltshire, Devon and Cornwall each gained one seat.
- Isle of Wight maintained its status as one constituency, the largest by electorate.
- The City of York was divided into two seats, neither overlapping part of North Yorkshire.
- The metropolitan counties of West Midlands (Birmingham) and the metropolitan counties of Greater Manchester, Merseyside, Tyne and Wear, South Yorkshire and West Yorkshire lost a seat each.
- Inner London gained one seat while northern parts of Outer London lost two.
- Herefordshire and Worcestershire, to reflect their full reinstatement as separate counties, were considered in separate reviews, leading to Herefordshire being split into two constituencies, each entirely within the county.
- Bath, Bristol and Somerset underwent arguably the most significant changes, gaining one seat overall, to reflect the abolition of Avon.
Proposed boundary changes
The Boundary Commissions submitted their final proposals in respect of the Sixth Periodic Review of Westminster Constituencies (the 2018 review) in September 2018. Although the proposals were immediately laid before Parliament they were not brought forward by the Government for approval. Accordingly, they did not come into effect for the 2019 election which took place on 12 December 2019, and which was contested using the constituency boundaries in place since 2010.
Under the terms of the Parliamentary Voting System and Constituencies Act 2011, the Sixth Review was based on reducing the total number of MPs from 650 to 600 and a strict electoral parity requirement that the electorate of all constituencies should be within a range of 5% either side of the electoral quota.
On 24 March 2020, the Minister of State for the Cabinet Office, Chloe Smith, issued a written statement to Parliament setting out the Government's thinking with regard to parliamentary boundaries. They propose to bring forward primary legislation to remove the statutory obligation to implement the 2018 Boundary Review recommendations, as well as set the framework for future boundary reviews in time for the next review which is due to begin in early 2021 and report no later than October 2023. It is proposed that the number of constituencies now remains at the current level of 650, rather than being reduced to 600, while retaining the requirement that the electorate should be no more than +/- 5% from the electoral quota.
- Member of Parliament
- Lists of electoral districts by nation
- United Kingdom general elections overview
- "The Parliamentary Constituencies and Assembly Electoral Regions (Wales) Order 2006". www.legislation.gov.uk.
- "The Parliamentary Constituencies (England) Order 2007". www.legislation.gov.uk.
- "The Parliamentary Constituencies (England) (Amendment) Order 2009". www.legislation.gov.uk.
- "The Parliamentary Constituencies (Northern Ireland) Order 2008". www.legislation.gov.uk.
- "A Guide to the 2013 Review" The Boundary Commission for England — retrieved 2012-12-19.
- "Electoral statistics, UK: 2017". ONS. Retrieved 7 August 2018.
- Baker, Carl; Uberoi, Elise; Cracknell, Richard (28 January 2020). "General Election 2019: full results and analysis". Cite journal requires
- "Parliamentary constituencies". www.parliament.uk. Retrieved 13 July 2019.
- "Hansard: 2 Jul 2001 : Column 82". www.parliament.uk. Hansard. Retrieved 13 July 2019.
- "Update: Strengthening Democracy:Written statement - HCWS183". UK Parliament. Retrieved 30 April 2020.
- Boundary Commission for N.I. Fifth Periodical Report (HM Command Paper 73) – Parliamentary Constituencies of Northern Ireland. Retrieved 2013-07-19.