UNIONS and Labour MPs warned Sir Keir Starmer against trying another “stitch-up” yesterday, amid reports the PM is trying to block Andy Burnham’s potential return to Westminster.

Britain’s biggest union Unison called for an end to Labour “control-freakery” while the Fire Brigades Union (FBU) said barring the Greater Manchester Mayor from standing would be a “democratic outrage.”

Mr Burham, who has made no secret of his leadership ambitions, faced a decision last night on whether to attempt to stand for Gordon and Denton.

The incumbent MP, former Labour minister Andrew Gwynne, said on Thursday that he would stand down citing “significant ill health” and advice from his doctor not to return to work.

As a sitting mayor, Mr Burnham needs the approval of Labour’s national executive committee (NEC) to stand, under party rules.

Several Labour sources told the BBC that they expected the committee to object on the grounds that this would trigger an election for the Greater Manchester mayoralty, risking a devastating loss to Reform UK.

It is also possible that the NEC would insist that there should be an all-women shortlist to boost the number of female MPs.

But the leaders of Unison and the FBU, which are represented on the committee, warned against any move to block Mr Burnham.

Unison’s Andrea Egan said: “I’m sure all trade unionists expect a democratic process for Gorton and Denton in which local party members decide who they want to represent them.

“We’ve seen enough control-freakery in the Labour Party and it has done our movement nothing but harm.”

And the FBU’s Steve Wright said: “It would be a democratic outrage if Andy Burnham was blocked from seeking selection as Labour’s by-election candidate in this seat.”

Mr Burnham is far more popular in north-west England than Sir Keir, Labour or Reform leader Nigel Farage, according to the latest polls.

Ipsos’s Keiran Pedley said “if anyone has a personal brand up there — it is him” yesterday, citing Mr Burnham whopping +25 favourability in the north-west, compared to Mr Farage on -29 and the PM at -40.

Although Mr Gwynne won his seat with 51 per cent of the vote, Labour’s support nationally has crashed since the election and Reform UK has vowed to “throw everything” at the seat.

There has also been speculation that Green Party leader Zack Polanski could throw his hat in the ring, with a spokesperson for his party saying that they were “prepped and ready to go for any future by-election.”

Jo White, who chairs the Red Wall group of Labour MPs, said: “Let the north decide who their Labour candidate should be for the Gorton and Denton by-election. A London stitch up will be a disaster for Labour.”

And Crewe and Nantwich MP Connor Naismith said: “Gorton and Denton deserves the best possible choice of candidates. I agree with the Prime Minister that our attention should be on delivering for the public, not speculating about future leadership contests.

“Any decision made to limit the choice would be wrong.”

Sir Keir has not commented on whether Mr Burnham should stand, saying the NEC would set out the process for choosing a candidate, and adding the mayor was “doing an excellent job” in Manchester.

Health Minister Stephen Kinnock told BBC Breakfast yesterday the selection process would “be like any other and those rules and procedures will be set in due course.”

Speaking on Thursday, Mr Burnham said people “shouldn’t rush to conclusions” and while he insisted he was “very focused on my role as mayor,” he did not rule out an attempt to return to Westminster.

The former cabinet minister has stood twice for the Labour leadership and revealed many backbenchers had urged him to return to Westminster ahead of Labour’s party conference last year. He has been an outspoken critic of the Prime Minister.

Greens leader Mr Polanski has roots in Greater Manchester, but has lived in London for a number of years.

Sir Keir’s team has form on fixing candidate selections. It was accused of a “total party stitch-up” and a “factional purge” when Jamie Driscoll was barred from the shortlist from the North East mayoralty. He resigned from the party citing the PM’s “contempt” for the region in July 2023.

Left-wing Faiza Shaheen’s deselection by the NEC as Labour candidate for Chingford and Woodford Green in May 2024 saw 50 local members resign in protest, and is widely blamed for Conservative Iain Duncan Smith retaining the seat amid a Labour landslide.

She labelled her disciplinary meeting a factional “kangaroo court.”