Westminster Parliamentary Constituencies

Introduction
Boundary change and geographic constitution
County and borough constituencies
Useful links

Introduction

Westminster parliamentary constituencies are the areas used to elect Members of Parliament (MPs) to the House of Commons, which is the primary legislative chamber of the UK and is located in Westminster, London. At the May 2005 election there were 646 constituencies, each electing one MP using the first-past-the-post system. The number of MPs in each part of the UK is as follows: Country Number of constituencies/MPs England 529 Scotland 59 Wales 40 Northern Ireland 18 United Kingdom 646

Click on the extract above to view the map of Westminster parliamentary constituencies, as at 5 May 2005* (3.9Mb, pdf)

Boundary change and geographic constitution

Constituency boundaries are determined by the Boundary Commissions (one each for England, Scotland, Wales and Northern Ireland). The commissions are required to undertake a general review every 8 to 12 years in order to ensure electoral equality - i.e. that the sizes of the electorates in each constituency are as similar as possible (currently about 70,000 electors, typically reflecting a total population of 90,000). General reviews normally lead to large-scale changes but the commissions may also carry out localised interim reviews. These can occur at any time, but usually only lead to minor changes.

Constituencies are generally based on whole or part local authorities unless there is a strong case to straddle boundaries - each case is decided on its merits; constituencies may not however split electoral wards/divisions. Note though that although constituencies are defined to reflect wards at the time of review, the changes are not implemented until the subsequent general election. Accordingly the constituencies used in the 1997 General Election were mostly based on the April 1994 ward boundaries used for the fourth general review, but a small number of constituencies used April 1995 boundaries and some were affected by subsequent interim reviews. The 1997 constituencies were used again in 2001, except for some mostly minor boundary changes in London and South East England resulting from interim reviews. The 2001 constituencies were used again in 2005, except for changes to the Scottish Westminster Parliamentary Constituencies, which reduced in number from 72 to 59.

The fifth general review was completed in 2007. It will lead to major change in England and Wales at the date of the next General Election, with the majority of constituency boundaries used at the May 2005 General Election set to change. Interim reviews prior to the next General Election are likely to lead to some minor changes to the boundaries defined in the review.

County and borough constituencies

Sometimes constituencies are referred to as either borough (burgh in Scotland) or county constituencies. Borough constituencies are predominantly urban whereas county constituencies are partly or mostly rural. Definitions are allocated by the Boundary Commissions and affect candidates' election expenses and also who can be the constituency's returning officer. If used, the designation is suffixed to the constituency name and is generally abbreviated: BC for borough constituency, CC for county constituency.

Boundary Commission for England's webpages: their document on the 'Review of Parliamentary Constituencies in England' is particularly useful for further explanation of the regulations of the boundary change process.

Area Names & Codes Files: access to the list of Westminster parliamentary constituencies.

Constituency Locata: identify your own constituency and MP using this House of Commons search facility. Simply type in your postcode!

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This page last revised: Tuesday, 5 February 2008