Jo Cox death: Parties stand down in killed Labour MP's seat as Corbyn and Cameron call for unity

David Cameron and Jeremy Corbyn have made a joint statement calling for the country to unite

Labour Party leader Jeremy Corbyn lays flowers while Commons Speaker John Bercow and Prime Minister David Cameron look on in Birstall, West Yorkshire, after Labour MP Jo Cox was shot and stabbed to death in the street (PA images)

Britain's main political parties have announced that they will not contest the parliamentary seat left vacant by the murder of Labour MP Jo Cox.

The Conservatives said this afternoon they would stand down in Batley and Spen "as a mark of respect" to the MP ahead of an unprecedented joint statement by Jeremy Corbyn and David Cameron.

The two party leaders, normally bitter rivals, jointly asked the nation to unite in a joint address in the constituency on Friday afternoon.

The Liberal Democrats and Ukip soon after confirmed that they too would not contest the seat, meaning Labour's candidate is very likely to be elected unopposed - barring a challenge by independents or minnows.

The news comes as it is announced that Parliament will be recalled on Monday to allow MPs to pay tribute to Ms Cox.

This afternoon's joint statement is a reversal of Mr Corbyn's policy of not sharing platforms with the Prime Minister, which has been in effect during the European Union referendum campaign.

Mr Cameron said the way to honour Ms Cox was to “redouble” her values of tolerance in the face of her killing.

“Where we see hatred, where we find division, where we see intolerance, we must drive it out of our politics, our public life, and our communities,” the Prime Minister said.

Jo Cox the day before her killing (Brendan Cox/Twitter)

“If we truly want to honour Jo what we must do is recognise that her values – service, community, tolerance – the values she lived by and worked by; those are the values we need to redouble in our public life in the months and years to come.”

Mr Corbyn said the correct response to the killing was to strengthen Britain’s democracy and free speech.

“We all need to come together to understand that everyone must have protection and security in order to function in a democratic society,” the Labour leader urged.

“Jo was an exceptional, wonderful, very talented woman, taken from us in her early 40s when she had some much to give and so much of her life ahead of her.

“It’s a tragedy beyond tragedy what happened yesterday. In her memory, we will not allow those people that spread hatred and poison to divide our society, we will strengthen our democracy, strengthen our free speech.”

The Speaker of the House of Commons John Bercow, who was also present, spoke of his admiration of the slain MP.

“Today I think everybody is united in grief, in horror, and in an overpowering respect for someone we came to know, whose talents we admired, and whose passion we admitted on a daily basis,” he said.

A Conservative spokesperson said this morning that the party "has decided not to contest the forthcoming by-election as a mark of respect to a much-loved and respected politician”.

Such a by-election would normally give other parties a chance to wrest control of the seat from Labour.

Former party chair Grant Shapps on Friday morning however suggested that Ms Cox’s replacement should be elected unopposed as a mark of tribute to her public service.

“I hope that in the sad by-election to follow, Jo Cox's constituency is left uncontested as a tribute to Jo's extraordinary public service,” he said in a tweet.

The date of any by election will not be set until Labour moves the writ to schedule it in the House of Commons.

Other parties have not yet said whether they will contest the by-election or not.

A vigil was held in Parliament Square last night to commemorate Ms Cox’s life. Another will be held on Friday evening, with thousands expected to attend.

West Yorkshire Police have arrested 52-year-old Thomas Mair in connection with the killing. They say they are not seeking any other individuals and that it was "localised" in nature.