There are currently 650 constituencies, each sending one MP to the House of Commons, corresponding to approximately one for every 92,000 people, or one for every 68,000 parliamentary electors.
While the Conservative – Liberal Democrat coalition governing after the 2010 general election had initially planned to reduce the number of MPs and constituencies to 600 during its term of office, Parliament voted in January 2013 to delay the boundary review this change would require.
[1] Section 6 of the Electoral Registration and Administration Act 2013[2] required that the next review report come by October 2018; that was done, but the delays continued.
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 historical county they were situated in, the state of representation was very imperfect.
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).
For the first time the total number of members of parliament was to be fixed (at 600) and a mathematical formula was prescribed for apportioning seats between the four parts of the United Kingdom.
They had a statutory duty to produce a final report on the review by 1 October 2018, but it was not submitted for approval and never implemented at all in 2019, with Parliament and the commissions keeping the 650 seats and the boundaries as drawn before 2010.
For the next election, scheduled for 2024, the newly redrawn constituency boundaries and recommendations, whose process began in January 2021, are expected to be reported no later than June 2023.
It also authorised the Lord Protector and Council of State to provide for the parliamentary representation of Scotland and Ireland.
Monmouthshire is treated as part of Wales throughout this section, although it was sometimes considered to be an English county before the twentieth century.
The House of Commons was increased from 650 to 651, by splitting Milton Keynes into two constituencies after a rare interim boundary review due to the growing size of the town.
Only 66 constituencies remained unchanged, in the greatest boundary re-organisation since the Great Reform Act.
Of the new constituencies two were in Essex, with one in each of Middlesex, Surrey, Kent, East Sussex, Hertfordshire, Cheshire, Hampshire, Staffordshire and Warwickshire.