Labour and the Liberal Democrats will not stand candidates in the by-election contest to find a successor to murdered Conservative MP Sir David Amess.

It comes after a Labour peer and former minister urged major opposition parties to honour past precedent by refusing to battle for the Southend West seat following the fatal stabbing of the Tory incumbent.

PA news agency understands that Labour is set to follow the principle established after Jo Cox’s murder in 2016 when parties which held Commons seats declined to select candidates in the subsequent Batley and Spen by-election, which was won by Tracey Brabin.

As a result of that move five years ago, it is understood Labour will refuse to contest the by-election in which voters will be asked to elect Sir David’s replacement after his tragic death on Friday.

A Liberal Democrat spokesman confirmed to PA that the party will not fight for the seat either when a polling date is set.

The decision backs what Lord Pendry, the former MP for Stalybridge and Hyde from 1970 to 2001, had called for in the wake of the killing of his old political associate.

He welcomed the show of cross-party unity in Leigh-on-Sea, where Sir David was stabbed to death at a constituency surgery event, as Boris Johnson and Labour leader Sir Keir Starmer came together to lay flowers on Saturday.

Lord Pendry told PA: “This is an occasion when you see the leader of the Opposition and the Prime Minister together, and it shows that our democracy transcends all that sort of thing.

“I think we should be saying that whoever the Conservatives put up, it is their seat because they were deprived of it, so they should have it back.

“I think all the major parties should stand aside in the interest of democracy and our own democratic way of life.”

Southend West has been held by the Conservatives since its creation in 1950, with Sir David elected on an increased majority of more than 14,400 votes at the 2019 general election.