LABOUR MPs demanded an urgent probe into Sir Keir Starmer’s appointment of Peter Mandelson as ambassador in Washington after the Prime Minister was forced to fire the disgraced envoy.

The pressure mounted as politicians on all sides questioned Starmer’s judgement in appointing the controversial New Labour grandee in the first place.

The sacking came less than 24 hours after Starmer had stoutly defended Mandelson in the Commons as the intensity of his friendship with paedophile financier Jeffrey Epstein came to light.

Further overnight revelations of Mandelson consoling and advising Epstein even after the latter’s conviction for involvement in child prostitution in the US sealed the ambassador’s fate.

A statement from the Foreign Office showed Starmer bowing to the inevitable, as opposition to Mandelson continuing in post was virtually unanimous among Labour MPs.

It said: “In light of the additional information in emails written by Peter Mandelson, the Prime Minister has asked the Foreign Secretary to withdraw him as ambassador. 

“The emails show that the depth and extent of Peter Mandelson’s relationship with Jeffrey Epstein is materially different from that known at the time of his appointment.

“In particular Peter Mandelson’s suggestion that Jeffrey Epstein’s first conviction was wrongful and should be challenged is new information. In light of that, and mindful of the victims of Epstein’s crimes he has been withdrawn as ambassador with immediate effect.”

The departure of the turbulent “prince of darkness,” as he was dubbed in the Blair years, is a blow to Starmer’s powerful chief of staff Morgan McSweeney, a protege of Mandelson and influential in his appointment. 

Starmer now has to explain why Mandelson was appointed in the first place, since his relationship with Epstein was already in the public domain.

Emily Thornberry, chair of the influential Commons foreign affairs committee, revealed that she had been blocked from questioning Mandelson at an earlier stage.

“Since the first rumours of his appointment, my committee has repeatedly asked — publicly and privately — to question Peter Mandelson,” she said.

”It is right that he has now been sacked. The Foreign Office should not have stopped us from asking questions. The government should welcome such scrutiny.”

And left MP Andy McDonald, who led calls for Mandelson’s sacking, demanded an inquiry into vetting failures.

“Clearly the appointment process didn’t pick up these issues, that’s self-evident. So can we have an assurance that there will be an inquiry into why that wasn’t the case,” he asked.

It is understood that the latest emails which finally pushed Starmer to act came from a long-defunct account. They revealed Mandelson professing “love” for Epstein, advising him to seek early release from his sentence for child prostitution, and assuring him that his imprisonment could not happen in Britain.

Green Party leader Zack Polanski said the whole scandal was a sign of “a dirty, broken political system.”

Mandelson follows other prominent personalities in British life in being laid low by association with the late financier, including Prince Andrew and ex-Barclays boss Jes Staley, but is perhaps the least surprising.

A friend who has known Mandelson for more than half a century told the Star: “He can’t help himself. He’s always been in awe of the rich.” He twice had to resign from government office under Tony Blair because of scandals involving millionaires and their money.

Former employment minister Justin Madders, booted out of the government at the weekend, drily commented: “Best sacking of the week by some distance.”

In a sulphurous reminder of the rancour that marked Mandelson’s years in New Labour, former party deputy leader Harriet Harman said: “It’s shameful that Peter Mandelson didn’t resign in the national interest and in the interest of the government, but he’s not that sort of person.”

Starmer now faces the challenge of finding a replacement at the court of President Trump. Tory former chancellor George Osborne has been mooted, and made the shortlist last time.

Reform leader Nigel Farage, a friend of Trump who has long coveted the role, threw his hat in the ring again, and made a compelling argument:

“If I was Starmer, I would offer it to me, because if I accepted it, it would get me out of the way, wouldn’t it,” he said.

But Liberal Democrat leader Ed Davey urged Starmer to “appoint an ambassador who will stand up to Trump, not cosy up to him and his cronies,”  which would certainly rule Farage out.