Modern representation: Great Britain and the United Kingdom

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1.8Forty-five Members from Scotland sat in the Parliament of Great Britain after the Union of 1707, and 100 from Ireland following the Union of 1801 which created the Parliament of the United Kingdom. By these successive additions the number of the Commons was increased to 658; and notwithstanding the changes effected in the distribution of the elective franchise by the Reform Acts in 1832, that number continued unaltered, except by the disenfranchisement of certain cities and boroughs for corruption, until the year 1885, when the number of the House was raised to 670 by the operation of the Redistribution of Seats Act of that year. By the Representation of the People Act 1918 the number of Members was increased to 707, but the reduction of the number of Members for constituencies in Northern Ireland under the Government of Ireland Act 1920, and the cessation of representation of constituencies in the rest of Ireland consequential on the establishment of the Irish Free State, reduced the number of Members of the House of Commons to 615.

As a result of the House of Commons (Redistribution of Seats) Act 1944, which made temporary provision for the subdivision of certain abnormally large constituencies (specified in the second schedule to the Act),1 the number of Members was increased by 25 to 640. This number was reduced by the Representation of the People Act 1948, to 625, subject to variation by Order in Council on the recommendation of the Boundary Commissions; such Orders in Council were made under the authority of the House of Commons (Redistribution of Seats) Act 1949 and since 1986 under the Parliamentary Constituencies Act 1986 (see para 2.3 ).

Although the 1986 Act, as passed, stated that the number of constituencies in Great Britain should not be ‘substantially greater or less than 613’, there had been an increase in the number of seats since 1948, and in 1986 there were 650 seats. Other rules for the redistribution of seats set down in the Act made it extremely difficult for the Boundary Commissioners to create 613 seats with electorates of broadly the same size.2 Accordingly the creation of new constituencies, because of the growth of the electorate in some areas, was not offset to the same extent by the reduction of seats where the electorate had fallen.

There are currently 650 Members of the House of Commons. In 2010, the coalition Government undertook to create ‘fewer and more equal sized constituencies', and subsequently the Parliamentary Voting System and Constituencies Act 2011 made provision to reduce the number of Members to 600 and to ensure more equal-sized electorates to within 5% above or below the electoral quota. The 2011 Act required the Boundary Commissions to report their recommendations for achieving this reduction to the Secretary of State in September 2013; this deadline was delayed until September 2018 by the Electoral Registration and Administration Act 2013. (see para 2.3 ).3

The 2018 recommendations from the Boundary Commissions were not implemented. The Parliamentary Constituencies Act 2020 removed the duty to implement the recommendations. The 2020 Act also cancelled the reduction in the number of Members, specifying instead that there shall be 650 constituencies. It made no change to the rules on more equal-sized constituencies.4


  1. 1. This partial measure of redistribution was recommended by the Speaker's Conference on Electoral Reform and Redistribution of Seats 1944, in their first report. (Letter from Mr Speaker to the Prime Minister, 24 May 1944; Cmd 6534.)
  2. 2. See also Boundary Commissions Act 1992 (c 55), s 3.
  3. 3. Electoral Registration and Administration Act 2013 (c 6), s 6.
  4. 4. Parliamentary Constituencies Act 2020 (c 25), ss 5, 10.