Where the election will be won and lost: Key targets and battlegrounds

North-west England will play a crucial role in determining the outcome of the next general election, new analysis shows.

The region is home to the number one target seat for Labour, Burnley, and the chief target for the Conservatives, Warrington South.

It also contains five of Labour’s top 10 targets and three of the Tories’ top 10.

Other key Conservative-Labour battlegrounds include the Midlands and Yorkshire, while most of the pivotal Conservative-Liberal Democrat contests are in southern England.

Scotland and Wales both hold opportunities for several parties to make gains.

But East Anglia could find itself largely overlooked during the campaign, with very few constituencies appearing on any battleground lists.

– How the targets are calculated

The top targets for the next general election are based on how easy or hard it would be for a seat to change hands.

This is done by calculating the change in the share of the vote in each seat, or swing, that would be needed for a party to make a gain.

The smaller the swing, the higher the seat is ranked on the list.

Labour needs a swing of only 0.13 percentage points, or 0.2 if written to one decimal place (as 0.1 would not be enough), to gain Burnley from the Conservatives.

The Tories would take Warrington South – which at the next election will be treated as a Labour defence because of boundary changes – on an even smaller swing of 0.06 (or 0.1) points.

Five other seats in Labour’s top 10 targets would fall to the party on a swing of 1.0 points or less, all of which are being defended by the Conservatives: Leigh & Atherton in Greater Manchester, High Peak in Derbyshire, Bangor Aberconwy in Wales, Wolverhampton West in the West Midlands and Bury South in Greater Manchester.

Bury North, Bolton North East in Greater Manchester, Watford in Hertfordshire and Chingford & Woodford Green in north London complete Labour’s top 10 – all Tory defences.

– Boundary changes

Leigh & Atherton, Bangor Aberconwy and Wolverhampton West are all examples of new seats at the next election.

They have been created as part of a UK-wide redrawing of constituency boundaries, which has been done to reflect changes in the size of local populations.

This is also why Bury South will be treated as a Conservative defence at the next election, even though its present MP, Christian Wakeford, defected from the Tories to Labour halfway through the current parliament.

The last time a major redrawing of boundaries took place was ahead of the 2010 general election.

In order to identify which seats on the new electoral map will be the parties’ top targets, and to work out the swing needed for these seats to change hands, a set of notional results for the last general election has been calculated to show what would have happened if that contest had taken place using the new boundaries.

These notional results have been compiled by Professors Colin Rallings and Michael Thrasher of the University of Plymouth, on behalf of BBC News, ITV News, Sky News and the PA news agency – all of whom will use the figures as the basis for reporting the gains and losses at the next general election.

For example, Burnley, Labour’s number one target, had a notional result in 2019 of the Tories on 40.46% of the vote and Labour on 40.19%, while Warrington South, the Tories’ top target, was 44.47% Labour and 44.35% Conservative.

This is why Warrington South will be treated as a Labour defence at the next election – and is considered the Conservatives’ top target – despite it being currently represented by the Tory MP Andy Carter.

– Key Labour and Conservative contests

The data shows that, of Labour’s top 50 targets, 10 are in north-west England, seven in Wales, six in the East Midlands and five each in the West Midlands and Yorkshire/Humber, with the remainder spread across the rest of the UK.

All of these will be treated as Conservative defences at the election – and all would fall on local swings from Tory to Labour of up to 5.4 percentage points.

Labour would need to perform much better to stand any chance of forming the next government, however.

The party needs a uniform nationwide swing from Conservative to Labour of 8.3 points to become the largest party in a hung parliament, and an even bigger swing of 12.7 points to gain an overall majority – more than the 10.2-point swing achieved by Tony Blair in 1997.

Two key constituencies to watch will be Chelsea & Fulham in London, which Labour would gain from the Conservatives on a local swing of 8.3 points, and Buckingham & Bletchley in Buckinghamshire, which the party would gain from the Tories on a local swing of 12.7 points.

Of the Conservatives’ top 50 targets, 11 are in Yorkshire/Humber, seven in north-west England and five each in the West Midlands and Wales – all areas that appear high on Labour’s list.

An exception is north-east England, which holds only two of Labour’s top 50 but nine of the Tories’ top 50, all of which are being defended by Labour.

Along with Warrington South, the Conservatives’ top 10 are all Labour defences and include two other seats in the North West: Wirral West in Merseyside and Heywood & Middleton North in Greater Manchester.

Three are in the West Midlands: Coventry North West, Coventry South and Warwick & Leamington; one is in Wales, Alyn & Deeside; and three are in London: Kensington & Bayswater, Beckenham & Penge and Dagenham & Rainham.

– Liberal Democrats’ targets

The Liberal Democrats face a very different battleground, with the majority of their resources likely to be focused in the southern half of the country.

More than half (28) of the Lib Dems’ top 50 target seats are spread across south-west and south-east England – and all of these are being defended by the Conservatives.

A local swing in these seats of five percentage points from the Tories to the Liberal Democrats would see the party pick up the likes of Cheltenham, Eastbourne and St Ives, while a 10-point swing would deliver them seats including Winchester, Woking and Didcot & Wantage.

Recent by-elections have seen the party take seats from the Tories on swings well above 10 points, however.

Were such a feat repeated at the general election, many more areas of southern England could turn orange, including the former Lib Dem heartlands of Devon North, Yeovil and Cornwall North.

Constituencies outside southern England that are on the Lib Dems’ top 50 list include the SNP-held seats of Fife North East and Dunbartonshire Mid in Scotland, and the Tory-held seats of Cheadle and Hazel Grove in north-west England.

But the Lib Dems’ number one target is in London: the Conservative-held seat of Carshalton & Wallington, which would change hands on a tiny local swing of 0.7 percentage points.

– SNP, Plaid Cymru, Greens and Reform

The number of constituencies in Scotland drops from 59 to 57 under the new boundaries, 48 of which will be treated as seats being defended by the SNP.

A uniform swing in Scotland from the SNP to Labour of 10 percentage points would see Labour take 15 of these SNP seats, potentially reducing the number of gains the party would need in England in order to form the next government.

However, there could be some three-way fights in Scotland, with the SNP-held Labour targets of Cowdenbeath & Kirkcaldy and Edinburgh North & Leith also appearing on the target lists of the Conservatives and Lib Dems respectively.

The SNP’s top three targets are all Tory defences: Aberdeenshire West & Kincardine, Dumfries & Galloway and Aberdeenshire North & Moray East.

Sweeping changes to the boundaries in Wales have reduced the number of constituencies from 40 to 32 – a process that has been particularly harsh for Plaid Cymru, which has seen the four seats it won in 2019 translate into just two seats to defend at the next election, Ceredigion Preseli and Dwyfor Meirionnydd.

Plaid’s top two targets will be the Tory-held Ynys Mon and Caerfyrddin, both of which are also Labour targets.

Bristol Central is the top target for the Greens, though they will need a hefty 16.3-point local swing to take the seat from Labour.

In turn, Labour would need at 17.2-point local swing to take the Greens’ only parliamentary seat of Brighton Pavilion.

Number one target for Reform UK, formerly known as the Brexit Party, will be Barnsley North: a seat where they notionally won 30% of the vote at the last election, and which they would gain at the next election on a 4.5-point local swing from Labour.

Separate analysis of target seats in Northern Ireland, which has a distinct party system of its own, will be produced nearer to the election.