Timeline of the 2023 periodic review of Westminster constituencies

[2] By every, routine, local government canvass reaching slightly fewer imminent attainers of the age of 18 effectively than the old system of household registration[2] a small group of LSE experts have blogged, this change very marginally favours the Conservatives.

[3] Local election offices are funded to implement mitigating measures to minimise any such disproportionate impacts.

[2] The Command Papers were sponsored and ordered by a Deputy Prime Minister, Nick Clegg, a Liberal Democrat.

Following three rounds of public consultation, all four Commissions submitted their final proposals to the Speaker of the House of Commons on 27 June 2023.

The Speaker immediately laid these before Parliament and the reports were published on the respective Commissions' websites the following day.

[5] The new boundaries were formally introduced into UK law on 15 November 2023 through The Parliamentary Constituencies Order 2023.

[1] (The original deadline of the end of October was missed by the government, which, according to the Act, must only happen in exceptional circumstances).

The 2018 periodic review of Westminster constituencies commenced following the 2015 general election and the four Boundary Commissions submitted their final recommendations to the Secretary of State on 5 September 2018[6][7] and made their reports public a week later.

[4] The Government's policy position regarding the process for the 2023 review was confirmed in a written statement, entitled Strengthening Democracy, by Minister of State for the Cabinet Office Chloe Smith on 24 March 2020.

[22] The commissions jointly calculated the relevant electoral quota/range to be used for the 2023 review and the allocation of parliamentary constituencies between the four nations.

[21] Of the 646 unprotected constituencies (Isle of Wight currently has only one seat), 236 had electorates within the permitted range, while 203 were below and 207 were above.

[29] The Commission for England subsequently worked with local authorities to produce updated data which included these 'prospective' wards.

[47] As the number of constituencies in Northern Ireland remains the same, changes were only necessary to bring some of the electorates within the permitted range and align boundaries with those of revised local government wards.

[49][50] The following table details the proposed changes, based on the commission's press release.

If the 2019 general election was re-run under the boundaries in the initial proposals, it was estimated that a further 23 seats would change hands.

The Commissions subsequently published these comments on their respective web sites and further six-week secondary consultation periods were then held, giving the opportunity for observations to be made on the comments made in the initial consultations.

After receiving over 45,000 comments over the previous two consultation periods, the Commission revised nearly half the proposed constituencies put forward in its initial review (including name changes).

[73] The Commission for Wales published revised proposals on 19 October 2022, with comments due no later than 15 November.

Overall, compared to the initial proposals, this would map out to three fewer seats won by the Conservative party at the 2019 general election and three fewer lost by the Labour party, the supervening (wider swing in votes) meaning only a net gain of ten for the Conservatives and net loss of five Labour MPs.

In November 2022, professors Colin Rallings and Michael Thrasher estimated the Conservatives would have won five additional seats in 2019, with Labour unchanged.

[61] All four Commissions submitted their Final Recommendations Reports to the Speaker of the House of Commons on 27 June 2023 and they were immediately laid before Parliament.

The final recommendations for England result in only 55 of the existing 533 constituencies remaining completely unchanged.

In accordance with the Parliamentary Constituencies Act, the Order in Council to formally introduce the new boundaries into UK law should have been approved by 28 October 2023 – 4 months after the publication of the final reports, unless "there are exceptional circumstances".