For the first time in nearly a week, all three of the main party leaders have been on the campaign trail and visiting battleground seats that will determine the outcome of the General Election.

Liberal Democrat leader Sir Ed Davey spent the day in two of his party’s targets in south-west England: Devon South and Yeovil.

Devon South is a new constituency at this election but would have had a notional Conservative majority in 2019 of 13,719, based on calculations by professors Colin Rallings and Michael Thrasher of the University of Plymouth.

A 12.7 percentage point-swing in the share of the vote from the Tories to the Lib Dems would see this seat change hands, ranking it at number 40 on the Lib Dems’ target list.

A profile of the Devon South constituency
A profile of the Devon South constituency (PA Graphics)

Sir Ed has been ticking off his party’s targets methodically since the start of the campaign, and has now visited 17 of the top 50, all of them Tory defences.

He also visited a further nine Tory-held seats that are outside his top 50, including his second stop on Monday, Yeovil (target number 52).

Yeovil has a symbolic place in Lib Dem history, being the seat once held by the party’s founding leader Paddy Ashdown.

The Conservatives have held it since 2015 and had a notional majority of 14,638 in 2019, but a swing of 13.6 percentage points would see the Lib Dems take it on July 4.

Sir Ed has now visited 29 seats since the start of the campaign, 26 of which are being defended by the Conservatives.

The other three are the safe Labour seat of Hackney South & Shoreditch, where he launched the Lib Dem manifesto; Cowdenbeath & Kirkcaldy in Scotland, won by the SNP in 2019 and more plausibly a Labour target at this election; and the safe Lib Dem seat of Bath.

A profile of the Southampton Itchen constituency
A profile of the Southampton Itchen constituency (PA Graphics)

Labour leader Sir Keir Starmer held one campaign event on Monday, in Southampton Itchen: a seat held by Labour from 1992 until 2015, when it was won by the Conservatives, who then held it at both the 2017 and 2019 elections.

Southampton Itchen is one of Labour’s top 50 targets (number 47) and would need a swing from Tory to Labour of 4.8 percentage points to change hands.

Sir Keir Starmer has now visited 29 seats in the course of the campaign, the same number as his Lib Dem counterpart, 21 of which are being defended by the Tories.

He has also held events in five Labour seats, two SNP seats in Scotland, and Brighton Pavilion in East Sussex which is being defended by the Greens.

A chart showing the number of seats visited by the main party leaders on the election campaign so far, with Rishi Sunak on 34 and both Keir Starmer and Ed Davey on 29
Seats visited by the main party leaders on the election campaign so far (PA Graphics)

Meanwhile, Prime Minister Rishi Sunak returned to the campaign trail on Monday after several days carrying out other engagements, including attending the G7 summit in Italy.

He began with a visit to the Rough 47/3B Bravo gas platform in the North Sea off the East Yorkshire coast, before travelling to the newly-created constituency of Grantham & Bourne in Lincolnshire, where his party is defending a huge notional majority of 22,393.

The size of the swing needed by Labour to win Grantham & Bourne seat is so enormous, 23.0 percentage points, that the seat ranks at number 334 on the party’s target list.

It is not the first constituency Mr Sunak has visited during the campaign with a Tory majority of over 20,000; he has also held events in Hinckley & Bosworth (where his party’s notional majority is 22,851), Thirsk & Malton (23,337), Northamptonshire South (23,671) and Honiton & Sidmouth (26,229).

The Prime Minister has visited 34 constituencies since the campaign began, of which 31 are Conservative defences.

He has visited only one Labour seat so far: Blyth & Ashington, a new constituency at this election, but one which would have had a notional Labour majority in 2019 of 6,118.

The other two seats in which he has held campaign events are Caithness, Sutherland & Easter Ross (won by the SNP in 2019) and Belfast East (won by the DUP).