Number of Westminster MPs - History

History

In the 16th century there were around 310 Members of Parliament, including representation at various points from Calais and Wales.

In 1654 the First Protectorate Parliament included elected representation from Scotland and Ireland. After the Third Protectorate Parliament in 1659 the Scottish and Irish members disappeared from Westminster until the unions of 1707 and 1801 respectively.

In 1654 England and Wales saw its first systematic redistribution of parliamentary seats ever. However in 1659 the representation of England and Wales reverted to the pre-Civil War pattern. When the Rump Parliament was recalled, later the same year, and the full Long Parliament was reinstated the following year its composition was exactly the same as before the Protectorate.

Only three new English constituencies, with a total of six seats, were enfranchised between the restoration of King Charles II in 1660 and the Reform Act 1832. As many of the constituencies were rotten boroughs, which had either decayed into insignificance centuries ago or had never been important settlements, whereas some major towns only participated in elections as part of the historic county they were situated in, the state of representation was very imperfect. By the Glorious Revolution of 1688 there were 513 MPs, until the Act of Union 1707 added 45 MPs for Scotland. These 558 were again increased to 658 by the Act of Union 1800, with the addition of MPs for Ireland.

Over the next 85 years the number of seats varied only slightly, as constituencies were disenfranchised for corruption and the seats were re-allocated some time later (see the lists below for details). The major redistributions of constituencies following the Reform Act 1832 and Reform Act 1867 both created a new House (elected in 1832 and 1868 respectively) with exactly 658 seats. The number of MPs had dropped to 648 by the dissolution before the General Election of 1885.

With the Redistribution of Seats Act 1885, introduced in the wake of the Reform Act of 1884, the size of the House was increased to 670 and remained unchanged until the Representation of the People Act at the end of the First World War.

The period between 1918 and 1922 saw the most MPs in the history of Parliament.

From 1922 the number of seats has fluctuated between 615 and 659. Unlike the position in many countries, such as the United States and Australia, seats are not allocated to different parts of the United Kingdom by a strict mathematical formula. The total number of seats result from the decisions of the four national Boundary Commissions, each applying the rules from time to time provided for by Parliament.

Up to the fifth general review of parliamentary boundaries, the usual effect of the interaction of the rules applied by the four national boundary commissions was to over-represent the non-English parts of the United Kingdom compared to England. The number of seats in each redistribution also tended to rise (although Northern Ireland was under represented between 1922 and 1983 as for most of that time it had a devolved government and from the 2005 redistribution Scotland used the same quota of average number of electors per constituency as England as it now has devolved institutions).

The Parliamentary Voting System and Constituencies Act 2011, amended the rules. For the first time the total number of Members of Parliament was fixed (at 600) and a mathematical formula was prescribed for apportioning seats between the four parts of the United Kingdom. As a result of the new legislation, the sixth general review of parliamentary booundaries has commenced. The four national boundary commissions have agreed the apportionment of seats. They have a statutory duty to produce a final report on the review by 1 October 2013.