A constituency is the geographical area that each Member of Parliament represents.
Jonathan Willis explains how MPs can represent their constituents' views
The United Kingdom is presently divided up into 646 constituencies, each of which elects one Member of Parliament to the House of Commons.
Four boundary commissions (one each for England, Scotland, Wales and Northern Ireland) monitor and review the size and number of constituencies.
They have a series of considerations to take into account such as the number of electors, the size of the constituency and local identities.
The aim of the commissions is to get the number of people entitled to vote in each constituency as near to the figure of the electoral quota as is practical.
Traditionally, Scotland and Wales have had more seats or constituencies represented in Parliament than their population would strictly warrant, i.e. they have a smaller average number of electors per constituency.
The Speaker of the House of Commons is the Chairman of the Boundary Commissions for England, for Wales and for Northern Ireland.
The Chairman of the Boundary Commission for Scotland is elected for a period of four years.
The boundary commissions were set up in 1944 under the House of Commons (Re-distribution of Seats) Act.
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