Boundary reviews

The Sixth Periodic Review of Westminster constituencies, which proposed reducing the number of constituencies from 650 to 600, was commenced in 2011, but temporarily stopped in January 2013. Following the 2015 general election, each of the four parliamentary boundary commissions of the United Kingdom recommenced their review process in April 2016.^[15][16][17] The four commissions submitted their final recommendations to the Secretary of State on 5 September 2018^[18][19] and made their reports public a week later.^{[20][21][22][18]} However, the proposals were never put forward for approval before the calling of the general election held on 12 December 2019, and in December 2020 the reviews were formally abandoned under the Schedule to the Parliamentary Constituencies Act 2020.^[23]

A projection by psephologists Colin Rallings and Michael Thrasher of how the 2017 votes would have translated to seats under the 2018 boundaries suggested the changes would have been beneficial to the Conservative Party and detrimental to the Labour Party.^[24][25]

In March 2020, Cabinet Office minister Chloe Smith confirmed that the 2023 Periodic Review of Westminster constituencies would be based on retaining 650 seats.^[26][27] The previous relevant legislation was amended by the Parliamentary Constituencies Act 2020^[28] and the four boundary commissions formally launched their 2023 reviews on 5 January 2021.^{[29][30][31][32]} They were required to issue their final reports prior to 1 July 2023.^[23] Once the reports have been laid before Parliament, Orders in Council giving effect to the final proposals must be made within four months, unless "there are exceptional circumstances". Prior to the Parliamentary Constituencies Act 2020, boundary changes could not be implemented until they were approved by both Houses of Parliament.

The boundary changes were approved at a meeting of the Privy Council on 15 November 2023,^[33] and came into force on 29 November 2023,^[34] meaning that the general election will be contested on these new boundaries.^[35]

Notional 2019 results

The election will be contested under new constituency boundaries established by the Sixth Boundary Review in 2023. Consequently, media outlets tend to report seat gains and losses as compared to notional results. These are the results if all votes cast in 2019 were unchanged, but regrouped by new constituency boundaries.^[36] Notional results in the UK are always estimated, usually with the assistance of local election results, because vote counts at parliamentary elections in the UK do not obtain figures at any level more specific than that of the whole constituency.

In England, seats will be redistributed towards Southern England, away from Northern England, due to the different rates of population growth. North West England and North East England will lose two seats each whereas South East England will gain seven seats and South West England will gain three seats.^[37] Based on historic voting patterns, this is expected to help the Conservatives.^[38] Based on these new boundaries, different parties would have won several constituencies with unchanged names but changed boundaries in 2019. For example, the Conservatives would have won Wirral West and Leeds North West instead of the Labour Party, but Labour would have won Pudsey and Heywood & Middleton instead of the Conservatives. Westmorland and Lonsdale, the constituency represented by former Liberal Democrat leader Tim Farron, is now notionally a Conservative seat.

In Scotland, 57 MPs would be elected, down from the 59 in 2019, with the following notional partisan composition of Scotland's parliamentary delegation:^[39] The Scottish National Party would remain steady on 48 seats, despite two of their constituencies being dissolved. The Scottish Conservatives' seat count of six would likewise remain unchanged. Scottish Labour would have retained Edinburgh South, the sole constituency they won in 2019. Had the 2019 general election occurred with the new boundaries in effect, the Scottish Liberal Democrats would have only won two seats (Edinburgh West and Orkney and Shetland), instead of the four they did win that year, as the expanded electorates in the other two would overcome their slender majorities.

Under the new boundaries, Wales will lose eight seats, electing 32 MPs instead of the 40 they elected in 2019. Welsh Labour would have won 18 instead of the 22 MPs they elected in 2019, and the Welsh Conservatives 12 instead of 14. Due to the abolition and merging of rural constituencies in West Wales, Plaid Cymru would have only won two seats instead of four. Nonetheless, the boundaries are expected to cause difficulty for the Conservatives as more pro-Labour areas are added to some of their safest seats.^[40]

In Northern Ireland, the notional results are identical to the actual results of the 2019 general election in Northern Ireland.

More information Party, MPs ...

Notional 2019 results on 2023 boundaries

Party		MPs
		2019 actual result	2019 notional result	Change
	Conservative	365	372	7
	Labour	202	200	2
	SNP	48	48
	Liberal Democrats	11	8	3
	DUP	8	8
	Sinn Féin	7	7
	Plaid Cymru	4	2	2
	SDLP	2	2
	Green	1	1
	Alliance	1	1
	Speaker	1	1

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Legal requirements

At the 2019 general election, in which the Conservatives won a majority of 80 seats, the manifesto of the party contained a commitment to repeal the Fixed-term Parliaments Act due to "paralysis at a time when the country has needed decisive action".^[41] In December 2020, the government published a draft Fixed-term Parliaments Act 2011 (Repeal) Bill, later retitled the Dissolution and Calling of Parliament Act 2022.^[42] This entered into force on 24 March 2022. The prime minister can again request the monarch to dissolve Parliament and call an early election with 25 working days' notice. Section 4 of the Act provided: "If it has not been dissolved earlier, a Parliament dissolves at the beginning of the day that is the fifth anniversary of the day on which it first met."

The Electoral Commission has confirmed that the 2019 Parliament must be dissolved, at the latest, by 17 December 2024, and that the next general election must take place no later than 28 January 2025.^[43][44]

Possible dates

As per the legal requirements above, the next election must take place in 2024, or in January 2025. The latter possibility is seen as unlikely by analysts, because it would require the general election campaign to encompass the Christmas holiday period. However, it is widely expected that the incumbent Conservative government will delay the election as long as possible while it trails the opposition Labour Party in opinion polling.^[45][46][47] On 18 December 2023, Sunak told journalists that the general election will take place in 2024, rather than January 2025.^[2] On 4 January, he suggested the general election would probably be in the second half of 2024,^[48] and later confirmed that, contrary to widespread speculation, it would not be held on the same day as the local elections on 2 May.^[49]

Universities and students' unions have warned that an autumn general election may not give students enough time to register to vote after moving to their university accommodation at the start of the autumn term, potentially disenfranchising hundreds of thousands of students.^[50] This would likely benefit the incumbent Conservative Party, as research from the 2019 general election has shown that younger people are much more likely to vote for the Labour Party than older people, and seats with large proportions of students are younger than average.^[51]

Whitehall officials discouraged the election being held around 5 November 2024, to prevent clashing with the 2024 United States presidential election, for major security and market implications could result if two Five Eyes countries were to hold general elections at the same time. The last time elections in the two countries overlapped was in 1964, when the elections were held less than three weeks before the United States presidential election that year.^[52][53]

MPs not standing for re-election

As of 21 April 2024, a total of 99 current members of Parliament have announced their intention not to stand for re-election. Four MPs — Nadine Dorries, Nigel Adams, Chris Skidmore (all Conservative) and Chris Pincher (independent, elected as Conservative) — announced their intention not to stand again but later resigned from Parliament before the election.^{[54][55][56][57][58][59]}

MPs deselected or seeking a new constituency

Some sitting MPs have not been selected by their party to recontest their seat (or a successor seat). Options available to these MPs include standing down, challenging their non-selection, seeking selection for another seat, and contesting the election under a different banner.

Former MPs seeking to return to Parliament

MPs changing constituencies

Due to boundary changes, most MPs standing for re-election will seek to represent a seat at least slightly different from their present seat. However, in some cases sitting MPs have secured selection to stand in a substantially or completely different seat from their present seat. They may happen because their seat is marginal and likely to be lost by their party, losing preselection to another candidate, boundary changes abolish their present seat or their present seat is redrawn in an unfavourable way in boundary changes.