The UK may be divided into 650 constituencies, but the next election will be decided in somewhere between 50 and 100 of them – roughly a tenth of the total.

Last time around, in 2017, 70 seats changed hands, and the Conservatives lost their overall majority, ending up with 317 seats while a resurgent Labour took 262.

A string of close finishes last time means there are 97 marginal seats that will change hands on a swing of 5% or less – and 31 of those are “hyper marginals”, held with a wafer-thin 1% majority.

These are the top 100 targets for the Conservatives. Boris Johnson’s campaign is particularly focused on the so-called “red wall” – a string of 50 seats stretching from the Vale of Clwyd in Wales to Great Grimsby in the east of England. They are Labour held seats that the party hopes to gain because the voters are pro Brexit, such as Crewe and Nantwich, target No 5 overall, where the party is chasing a majority of 48. The Conservatives are hoping for up to 10 gains in Wales, including many Labour seats in the north such as Wrexham, its 35th target, a “red wall” seat held with a majority 1,832. The Yorkshire and Humber region is also a key battleground, where the Conservatives are chasing seats such as Great Grimsby. It is target No 45, and Labour’s majority is 2,565. Nationally, the Conservatives need to gain nine more seats across the country to win an overall majority of 326. The ninth most winnable seat outside Scotland is Stroud in Gloucestershire, majority 687. These are the top 100 targets for Labour, and are more scattered around the UK. They are largely Conservative held, in smaller cities or on the suburbs of major urban centres. The party needs 64 more seats for an overall majority of 326, the last of which is East Kilbride in Scotland, SNP majority of 3,866. If Labour wins 28 seats it becomes the largest party at Westminster on 290 seats. Target 28 is Pendle in the north-west, with a Conservative majority of 1,279. Key battlegrounds are in the West Midlands. Stoke-on-Trent South is the party’s 17th target seat, with a Conservative majority of 663). Winning Worcester would be a good night: the seat is target No 44, and has a Conservative majority of 2,490. Watch also the east Midlands. Northampton South, target No 27, is Con held with a majority of 1,159. On a good night the party regains North East Derbyshire, taken by the Conservatives in 2017 with a majority of 2,861. The Lib Dems' top 25 target seats are scattered around the country. Its most winnable seat is Fife North East, held by the SNP with a majority of two. But target No 25 is Taunton Deane, which has a Conservative majority of 15,887. The party is hoping to make gains in the south-west from the Conservatives in leave-supporting seats. The top two targets are St Ives (Conservative majority 312) and North Devon (Conservative majority 4,332). Pro-remain London is important for the Lib Dems. They are the favorites in Richmond Park (Conservative majority 45). Scotland has many marginal seats. The SNP is hoping to gain seats from the Conservatives in the north-east, such as Banff and Buchan (Conservative majority 3,693) which could take it just over 50 seats in Westminster. Northern Ireland could be crucial in a hung parliament. The DUP is under pressure in Belfast South (majority 1,996). Sinn Féin’s tightest seat is Foyle (majority 169) where it faces a challenge from the SDLP.

Target seats source: http://www.electionpolling.co.uk