Starmer’s comments come amid growing calls from within Downing Street and senior figures in Labour to reverse Brexit.

David Lammy, the Deputy Prime Minister, broke ranks by refusing seven times to rule out the prospect.

He claimed that rejoining the customs union was not “currently” the Government’s policy, but that it was “self-evident” that other countries had “seen growth” after doing so.

Starmer rebuked Lammy following the remarks, with his spokesman insisting more than 10 times that rejoining the customs union remained one of the Government’s “red lines” and was not its policy.

Closer relationship

However, recently the Prime Minister has been openly arguing for a closer relationship with Brussels.

In a speech last week, he said it would be “utterly reckless” to use Brexit as “a template for our future foreign policy” and pledged a “closer relationship” with the EU by the end of Labour’s term in government.

The push for stronger ties with the bloc follows concerns that the measures announced in last month’s Budget will fail to secure sufficient economic growth for the UK.

Starmer’s comments on Rayner’s potential return come after the Telegraph reported that allies of Wes Streeting, the Health Secretary, were pressing her to sign up to a “joint ticket” for the Labour leadership.

The Telegraph has also revealed that Unite, Labour’s biggest union backer, is considering a vote on splitting from the party in a blow to Starmer’s premiership.

Rayner had the closest relationship with the unions of any of Starmer’s team and was a member of Unite, until officials suspended her earlier this year following a row over the Birmingham bin strikes.

In the interview, Starmer said he missed Rayner and claimed misogyny had played a part in the level of criticism she and Rachel Reeves, the Chancellor of the Exchequer, had faced in recent months.

After describing Rayner as “the best social mobility story this country has ever seen”, he was asked if he missed his former deputy. He replied: “Yes, of course I do. I was really sad that we lost her.

“As I said to her at the time, she’s going to be a major voice in the Labour movement.”

Pressed on whether she would return to the Cabinet, he replied: “Yes. She’s hugely talented.”

Last month, Kemi Badenoch, the Tory leader, argued during Prime Minister’s Questions that any return for Rayner should be on the condition that “she must pay back the £40,000 of property taxes she avoided”.

Last week, a source close to the former deputy prime minister said she would “not be played like a pawn” after reports of a deal for her and Streeting to run for the Labour leadership.

The source said: “there is no vacancy and there is no pact”, after the Telegraph reported that allies of Streeting were pressing Rayner to sign up to a “joint ticket” for the top job.

One ally of Rayner told the Daily Mail that she had rejected several offers from the Prime Minister so far, adding: “She wants to be free to develop her own agenda from outside the Cabinet”.

PM: I won’t quit

Starmer also insisted that he had no intention of stepping aside before the next election.

He said: “When I took over the Labour Party, everyone said to me: ‘You’re not going to be able to change the party’. We ignored that and carried on.

“Then they said to me: ‘You’re not going to be able to win an election’. We got a landslide Labour victory.

“Now, 17 months into a five-year Labour term, they say: ‘You’re not able to change the country’.

“Every time we’ve been in this position, we’ve defied them. And that’s what I intend to do.”

Labour continues to poll at an average of 18% of the vote, with one poll this week putting the party as low as 14% far below Nigel Farage’s Reform UK on 27%.

The Telegraph revealed that MPs close to the Health Secretary had promised Rayner a Cabinet role, and perhaps a return to being deputy prime minister, if she backed a future Streeting leadership run.

Streeting is understood to have told Rayner last week in the Commons that the pair should have a catch-up soon, raising eyebrows among her allies.

A spokesman for Streeting called it a “silly season” story, while a source close to Rayner said there was “no pact”.

Last month, Streeting also denied plotting to remove Starmer, describing the claims as “self-defeating nonsense” and joking about Celebrity Traitors, insisting he was “a faithful”.

Downing Street said it had not briefed reporters against Streeting, but senior No 10 figures were sufficiently concerned by something to tell journalists Starmer would fight any potential leadership contest.

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