Andy Burnham may be facing a civil war from within his own Cabinet after opening the door to freedom of movement with the EU. His own Home Secretary, Shabana Mahmood, fears the scheme could undermine her efforts to control the border after she only found out about his plan after it broke in the national press. On Sunday, Mr Burnham told a national newspaper he would be open to a freedom of movement scheme.

When challenged by reporters on Monday, the Prime Minister suggested that no such decision would be made without putting it to a referendum โ€“ something his own spokesperson walked back from later in the same day. Mr Burnham, an ardent Remainer who campaigned for and voted to stay in the EU โ€“ and then demanded a second referendum when he lost โ€“ on Monday blamed Brexit for the small boats crisis.

Ms Mahmood has repeatedly suggested that she does not believe the historic vote to leave the EU is to blame for Britain’s weak borders.

A Labour insider told the i newspaper that the Home Secretary was โ€œfuriousโ€, with a government source adding that the Prime Ministerโ€™s remarks had โ€œunderminedโ€ her strategy to tackle out-of-control immigration.

In an interview with The Sunday Times, Mr Burnham said that he wanted an โ€œhonest discussionโ€ with the British public about a return to freedom of movement, all as part of a new relationship with the EU.

He added: โ€œI think you have to have a very factual, quite evidence-based debate about this.โ€

On Monday, he repeated his claim that he also wanted to see the country back into the EU โ€œin my lifetimeโ€, a claim initially made last year. His spokesperson said that this was his โ€œpersonal opinionโ€ and not that of the Government, just of the man who leads it.

The Prime Minister argued that migration has changed since Brexit, although he failed to provide data to back this up and his spokesperson likewise could not do so.

Before Brexit, he suggested, EU migrants were โ€œgenerally younger peopleโ€ who stayed for a few years before returning home.

Other members of the Cabinet are said to have been angry at not being consulted as well. One insider said: โ€œHe doesnโ€™t seem to realise the weight his comments have as Prime Minister. He still seems to be acting like he is a mayor.โ€

Mr Burnham is due to meet eurocrats next month where he will hash out a deal with the EU โ€“ a deal in which his spokesperson says none of Labourโ€™s โ€œred linesโ€ in their last manifesto will be crossed.

Brexiteers had reacted with fury last night after Mr Burnham’s dithering on Europe, with Reform UK’s Nigel Farage warning he was ready to refight Brexit, telling the Daily Express – “hold my jacket”.