The 2023 Periodic Review of Westminster constituencies was the most recent cycle of the process to redraw the constituency map for the House of Commons. The new constituency borders were approved by the Privy Council on 15 November 2023^[1] and came into law on 29 November 2023.^[2]

Quick Facts Parliamentary Constituencies Act 2020, Long title ...

Parliamentary Constituencies Act 2020
Act of Parliament
Parliament of the United Kingdom
Long title	An Act to make provision about reports of the Boundary Commissions under the Parliamentary Constituencies Act 1986; to make provision about the number of parliamentary constituencies and other rules for the distribution of seats; and for connected purposes.
Citation	2020 c. 25
Dates
Royal assent	14 December 2020
Status: Current legislation
Text of statute as originally enacted
Text of the Parliamentary Constituencies Act 2020 as in force today (including any amendments) within the United Kingdom, from legislation.gov.uk.

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The process for periodic reviews of parliamentary constituencies in the United Kingdom is governed by the Parliamentary Constituencies Act 1986, as amended by the Parliamentary Voting System and Constituencies Act 2011 and subsequently by the Parliamentary Constituencies Act 2020.^[3]

The 2023 review was the successor to the 2018 Periodic Review of Westminster constituencies, which was ultimately abandoned after it failed to pass into law. After abandonment of several previous reviews since 2015, the 2023 review was set to be the first review based on electoral registers drawn up using Individual Electoral Registration, which Parliament approved from 2014–15, an anti-fraud and personally empowering system that is in place in most of the world, replacing the older household registration that had been condemned by the worldwide Office for Democratic Institutions and Human Rights (OSCE/ODIHR).^[4] By every, routine, local government canvass reaching slightly fewer imminent attainers of the age of 18 effectively than the old system of household registration^[4] a small group of LSE experts have blogged, very marginally favours the Conservatives.^[5] Local election offices are funded to implement mitigating measures to minimise any such disproportionate impacts.^[4] The Command Papers were sponsored and ordered by a Deputy Prime Minister, Nick Clegg, a Liberal Democrat.

Under current legislation, the four Boundary Commissions of the United Kingdom were required to report on their next review of the boundaries of parliamentary constituencies before 1 July 2023.^[3] In order to meet this deadline, the Commissions began their work on 5 January 2021. 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.^[6] The new boundaries were formally introduced into UK law on 15 November 2023 through The Parliamentary Constituencies Order 2023.^[7] (The original deadline of the end of October was missed by the government, which, according to the Act, must only happen in exceptional circumstances).

A description of the review process is detailed in Timeline of the 2023 Periodic Review of Westminster constituencies.

The four Boundary Commissions formally launched their 2023 reviews on 5 January 2021,^{[8][9][10][11]} to coincide with the release by the Office for National Statistics (ONS) of electorate data from analysis of the electoral registers that had been published on 2 March 2020.^[12] 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. The English commission further divided its allocation between the nine regions of England.

The electorate of the United Kingdom, comprising 650 constituencies, as determined by the ONS, was 47,558,398 on 2 March 2020. The electorate of the five protected constituencies – Isle of Wight (two seats), Na h-Eileanan an Iar, Orkney and Shetland, and Ynys Môn – amounted to 220,132, leaving 47,338,266 to be distributed between the remaining 645 constituencies, which gave an electoral quota of 73,393. Each non-protected constituency must have an electorate which is within 5% of this quota, which gave a permitted range of 69,724 to 77,062.^[8] In Northern Ireland the legislation allows for a wider range, in certain prescribed circumstances, from 68,313 to 77,062.^[11]

All four Commissions submitted their Final Recommendations Reports to the Speaker of the House of Commons on 27 June 2023. These were immediately laid before Parliament and the reports were published on the respective Commissions' websites on 28 June 2023.^{[14] [15] [16] [17]}

In total, there are 211 newly named constituencies, with the same number of seat names no longer being used (comprising just under one third of the total of 650). These constituencies are listed alphabetically below. Note that a constituency name remaining the same or changing does not necessarily correlate with how much the seat's boundaries change, or whether the constituency would be seen as a "new constituency". For example, the pre-2023 Burton changes name to become the post-2023 Burton and Uttoxeter, but its boundaries remain identical; on the other hand, the constituency name Newcastle upon Tyne North remains the same after the review, but the majority of the post-review constituency covers different territory to the pre-review constituency, with only 43% of the pre-2023 Newcastle upon Tyne North remaining in the new seat after the review.

An existing seat can be regarded as being linked to a newly named seat where part of the existing seat contributes the largest part of the newly named seat. There are a total of 187 linked constituencies, many of which involve significant changes resulting from the knock-on impact of new or abolished seats within review areas. However, some arise from the consultation process and involve only minor changes. The table below lists those constituencies with name changes, indicating the extent of the changes by reference to the proportion of the old constituency included in the new constituency, or the proportion of the new in the old, which ever is the lesser:

• None – name change only
• Minor – greater than 90%
• Moderate – between 75% and 90%
• Major – between 50% and 75%
• Wholesale – less than 50%

Sources:

• Electoral Calculus – New Constituency Boundaries for 2023^[36]
• House of Commons Library – Boundary review 2023: Which seats will change in the UK?^[37]

The list below indicates those constituencies which have retained their names, but where boundary changes have resulted in major changes – where the proportion of the existing electorate included in the redefined constituency or vice versa, which ever is the lesser, is less than 75%.

• List of United Kingdom Parliament constituencies (2024 to present) by region