Keir Starmer’s premiership is hanging by a thread this weekend as new details about Peter Mandelson’s friendship with the convicted paedophile Jeffrey Epstein continue to drip into the public consciousness.

When the prime minister sacked Mandelson as the UK’s ambassador to Washington over his Epstein ties in September, he must have hoped the scandal was dealt with. The events of the past week show how wrong he was.

The latest chapter in the saga was triggered by the US Department of Justice publishing more than three million documents on the late sex offender and his connections to the rich and powerful.

The files revealed that Mandelson was even more entwined with the disgraced financier than previously assumed – putting Starmer’s judgement in appointing him to the plum diplomatic role into sharp focus.

Amid mounting anger from the public and his own MPs, the prime minister ended up apologising on Thursday for ever believing Mandelson’s “lies”.

Here’s a breakdown of how we got to this point – and what might happen next.

Mandelson has been in Labour circles for decades, often referred to as the “Prince of Darkness” because of his ruthless nature, capacity for scandals and love of political intrigue.

He worked as the director of communications to then-party leader Neil Kinnock in the 1980s before being elected as the Labour MP for Hartlepool in 1992.

A key architect of the New Labour project, he helped Tony Blair win the party leadership in 1994 and ran Labour’s successful general election campaign in 1997.

Blair rewarded Mandelson with the post of minister without portfolio, a roving commission which gave him enormous power over the government machine.

However, the personal frailties – and the attraction to money – which would later bring about his downfall led to his resignation after barely a year when he failed to declare a loan from a cabinet colleague whose business dealings Mandelson’s own department was investigating.

After a year on the backbenches licking his wounds, Blair brought him back into the cabinet as Northern Ireland secretary the following year, at the time a key role as the peace process faltered.

But once again, barely a year later, Mandelson was forced to resign, this time for lying about his role in brokering a British passport for a wealthy donor to the Millennium Dome project.

After famously declaring he was “a fighter, not a quitter” when retaining his Hartlepool seat in 2001, Mandelson stood down as an MP in 2004 to become a European trade commissioner, a post he held until he made another dramatic political comeback in 2008.

Gordon Brown, who had succeeded Blair the previous year, stunned Westminster by making Mandelson – his New Labour nemesis – a life peer and appointing him business secretary and de facto deputy prime minister.

He finally left frontline politics, apparently for good, when Labour lost the 2010 general election.

Despite his complete lack of diplomatic experience, Mandelson was appointed the UK’s ambassador to Washington a year ago.

He quickly established a rapport with President Donald Trump and was a key figure in negotiations on a UK/US trade deal and technology partnership.

Mandelson also helped to smooth over American concerns around the UK government’s decision to hand sovereignty over the strategically-important Chagos Islands to Mauritius.

His return to the heart of British politics was seen as a reward for his years of behind-the-scenes work with Morgan McSweeney – now Starmer’s chief of staff – to help return Labour to government.

McSweeney is known to have pushed the PM to give Mandelson the ambassador’s role, a judgement call which has intensified calls from Labour MPs for him to be sacked.

The nature of their friendship has come out in drips and drabs over the years. Here’s a breakdown of what is currently public knowledge – and when it was first revealed.

A Financial Times report from June 2023 unveiled how an internal JP Morgan report, dating back to 2019, noted Epstein’s “particularly close relationship with Prince Andrew the Duke of York and Lord Peter Mandelson, a senior member of the British government”.

The report was commissioned to shed light on JPMorgan’s 15-year relationship with Epstein and refers to a range of meetings between the disgraced financier and Mandelson.

The dossier also found Mandelson had stayed at Epstein’s lavish townhouse in Manhatten when he was the UK’s business secretary while the convicted criminal was in prison for soliciting underage sex from a minor.

Mandelson was appointed as US ambassador in February last year, after going through routine due diligence and security vetting.

When asked about his Epstein connection by the Financial Times’ George Parker during an extensive interview, the former Labour cabinet minister said: “I regret ever meeting him or being introduced to him by his partner Ghislaine Maxwell.”

Maxwell is currently in prison for recruiting and trafficking underaged girls for the financier.

Mandelson added: “I regret even more the hurt he caused to many young women.”

However, according to the FT report, “an icy chill” then descended during their conversation on the train, and Mandelson added: “I’m not going to go into this. It’s an FT obsession and frankly you can all fuck off. OK?”

When later asked about Mandelson’s language, the prime minister’s spokesperson told reporters: “The prime minister has made clear the expertise and the experience Lord Mandelson has in relation to becoming ambassador to the US.”

The seeds of Mandelson’s political demise were sown last autumn, when US lawmakers released a tranche of documemts relating to Epstein.

They included a “birthday book” which contained a message from Mandelson in which he described Epstein as his “best pal”.

But it was a further revelation, that Mandelson told Epstein in an email that “your friends stay with you and love you” even as he was facing child underage sex charges in 2008, that proved to be the final straw.

Despite telling MPs that he had “confidence” in his ambassador, Starmer eventually sacked Mandelson, just seven months after appointing him.

“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,” the Foreign Office said.

Despite being sacked in disgrace, Mandelson appeared poised to make another remarkable comeback thanks to a series of high-profile media appearances at the start of this year.

They included an interview on Sunday with Laura Kuenssberg, the BBC’s flagship political programme.

However, he caused outrage when he failed to apologise to Epstein’s victims, saying only that he was sorry “for a system” which did not listen to victims’ voices.

“That system gave him protection but not them,” he said. “If I had not known, or if I was in any way complicit or culpable, of course I would apologise for it.”

After an angry backlash, Mandelson rowed back the following day, saying: “I did not want to be held responsible for his [Epstein’s] crimes of which I was ignorant, not indifferent, because of the lies he told me and so many others.

“I was wrong to believe him following his conviction and to continue my association with him afterwards. I apologise unequivocally for doing so to the women and girls who suffered.”

A new tranche of documents from the US’s Department of Justice (DoJ) came out at the start of February and finally sealed Mandelson’s fate.

They appeared to show he had accepted $75,000 from the disgraced financier between 2003 and 2004, though Mandelson has said he has no recollection of receiving those payments and did not know if the documents were genuine.

But amid mounting public anger, he announced he was quitting the Labour Party to avoid “further embarrassment” last Sunday.

The scandal has only intensified since then, with Mandelson now facing a criminal investigation over allegations he passed market sensitive information to Epstein when he was business secretary and the government was dealing with the aftermath of the global financial crash.

Responding to the revelations, Starmer said Mandelson had “betrayed” Britain.

Other emails show Mandelson and Epstein sharing crude jokes when the latter was released from prison – an occasion described as “Liberation Day” by the peer.