Just six months ago Peter Mandelson seemed unassailable as the UK’s ambassador to the US, one of the most vaunted positions in British diplomacy. As our man in Washington, Mandelson appeared to have used his skill for schmoozing, learned over years as a cabinet minister and a European commissioner, to secure a good relationship with the tricky Trump administration. He was considered instrumental in securing a relatively favourable US trade deal for the UK.

He was also an influential voice in Labour politics with the ear of the prime minister and his inner circle, notably his friend and protege Morgan McSweeney, Starmer’s then chief of staff.

Mandelson’s arrest on Monday marks one of the quickest and steepest descents ever seen in British public life.

It began when US lawmakers released some of the Epstein emails in September 2025.

In one letter from 2003 Mandelson called Epstein “my best pal”. In a birthday message he described Epstein as an “intelligent sharp-witted man”. It detailed what appeared to be a close relationship and referred to Epstein’s “‘interesting’ friends”. Mandelson’s message about Epstein added: “Very occasionally, taking you by surprise in some far off places … Or in one of his glorious homes he likes to share with his friends (yum yum) … But wherever he is in the world, he remains my best pal!”

And an email from Mandelson to Epstein in 2008 said he would “fight for early release” when the disgraced financier was facing charges of soliciting sex.

Mandelson defended himself and said he regretted ever meeting Epstein. “I relied on assurances of his innocence that turned out later to be horrendously false,” he told the BBC.

But he also conceded to the Sun that more “embarrassing” messages to Epstein were likely to emerge.

Keir Starmer initially backed Mandelson in the face of Kemi Badenoch’s claims that his position as ambassador was untenable. At PMQs on 10 September, Starmer said he had full confidence in Mandelson. But only a day later sacked him over the Epstein messages.

Explaining the move, the Foreign Office said the messages showed the “depth and extent of Peter Mandelson’s relationship with Jeffrey Epstein is materially different from that known at the time of his appointment”.

But in June 2023 the Financial Times had revealed that a JP Morgan report had found evidence Mandelson had stayed in Epstein’s Manhattan townhouse in 2009 while Epstein was in jail.

As Mandelson signalled, worse was to come. The emails released in September suggested he was in contact with Epstein until 2010. But in November new emails released by the US House oversight committee showed he remained in close contact with Epstein until at least 2016.

In December 2025, as more emails began to be released, Mandelson said he thought he was kept away from Epstein’s crimes because he is gay.

In January this year, 3m Epstein files were released by the US Department of Justice. They revealed that Epstein had sent thousands of pounds in bank transfers to Mandelson and his partner and now husband Reinaldo Avila da Silva.

The money was sent in September 2009, about two months after Epstein was released from prison.

In a January 2026 interview with the BBC’s Laura Kuenssberg, Mandelson initially declined to apologise for his friendship with Epstein, stating he was “not culpable” and did not know the extent of Epstein’s crime.

After a public backlash at his remarks, Mandelson then apologised for his links to Epstein.

The latest batch of emails from the US justice department also suggested that Mandelson passed on market-sensitive information to Epstein while serving in Gordon Brown’s government as trade secretary.

In a 2009 email Mandelson told Epstein the Treasury was “digging in” on potential new taxes on bankers’ bonuses. Two days later, Epstein asked whether Jamie Dimon of JP Morgan should call the chancellor, Alistair Darling. In reply, Mandelson said he should “mildly threaten” the chancellor.

Another 2009 email appeared to be tipping off Epstein about £20bn of saleable assets by the UK government. He also gave Epstein the heads-up on Gordon Brown resigning as prime minister in 2010.

These revelations infuriated Brown and others. Writing in the Guardian, the former prime minister said they were “a betrayal of everything we stand for as a country”.

The communities secretary Steve Reed said Mandelson had “a moral obligation” to testify to US Congress about what he knew about Epstein.

Faced with mounting pressure, Mandelson resigned his membership of the Labour party on 1 February. There were also widespread calls to strip him of his peerage.

A week later on 8 February, McSweeney resigned as Starmer’s chief of staff. In a bid to take the heat off Starmer, McSweeney said he took full responsibility for Mandelson’s appointment as ambassador.

Last week Andrew Mountbatten-Windsor was arrested on suspicion of misconduct in public office when he was trade envoy. It was Mandelson who secured the then Prince Andrew the job in 2001, according to his biographer Andrew Lownie.

Today Mandelson was arrested on suspicion of the same offence. He denies any wrongdoing. The first batch of the Epstein emails cost Mandelson his job. The last batch may yet cost Mandelson his liberty.