Peter Mandelson flew into a panic at a Mail on Sunday front page suggesting the White House could block his appointment as US ambassador, the files reveal.

The January 2025 story - headlined 'Team Trump's Revenge on Starmer for 'Meddling' in US Election' - saw the architect of New Labour frantically emailing Number 10.

Allies of Mr Trump told the paper that Labour looking for supporters to travel to the US to campaign for rival Kamala Harris would not be forgotten lightly.

That saw Mandelson emailing the now-former Downing Street communications chief Matthew Doyle, demanding to know why more was not being done to squash the reports.

Writing alongside a picture of the article in January 2025, Lord Mandelson asked why then-ambassador to the US, Karen Pierce, was not calling Mr Trump's chief of staff and 'insisting it stops'.

The MoS reported that Trump advisers were debating whether to put Sir Keir 'at the back of the queue' of world leaders invited to Washington after his inauguration.

One added that the Prime Minister was 'gonna have to eat humble pie' if he wanted a speedy meeting, and that to humiliate him further, Lord Mandelson's appointment might be blocked.

Mr Trump's team were also said to have met Reform UK members in London, in an attempt to help Nigel Farage become prime minister.

Fretting over the article, Lord Mandelson asked Doyle: 'I think this is being turned into something big. Why isn't Karen calling [White House chief of staff] Susie Wiles and insisting it stops?'

He stressed it was 'too late' and 'not enough' that the deputy head of the UK mission in the US was due to meet Mr Trump's team the following day.

'Does the UK ambassador even follow what's happening?' he asked. 'Let's hope the BBC doesn't take it up'.

It comes after Mandelson 'went tonto' as he raged at Downing Street's chaotic efforts to secure a ministerial 'red box' for Donald Trump, newly published emails showed.

The release of the latest tranche of government files related to Mandelson's spell as US ambassador has revealed No. 10's frantic scramble to arrange the gift.

Mr Trump is said to have wanted a 'red dispatch box with the gold crest and lettering' to mimic the official boxes carried by UK ministers, according to the emails.

Ahead of the US President's state visit to Britain in September last year, Whitehall officials were shown to have devoted considerable efforts to obtaining the present.

The documents published on Monday also detailed how Mandelson intervened in an apparent complaint about the time being taken to secure the gift.

In an email to Keir Starmer's then-chief of staff, Morgan McSweeney, in late August 2025, the disgraced peer compared the situation to TV's The Thick Of It.

He added he had 'gone tonto on this' in the heavily redacted message to the Prime Minister's top aide.

The disgraced peer ended up resigning just days before Mr Trump's visit to Britain, in September 2025, following fresh revelations about his links to Jeffrey Epstein.

In the final weeks of his time as US ambassador, Lord Mandelson was revealed to have emailed Mr McSweeney on August 26 that year about Mr Trump's proposed gift.

He wrote: 'The saga goes on. See Olly email. This is like something out of Thick of it.

'We are now facing the red box being presented by [redacted] after [redacted] with [redacted]. I have gone tonto on this.'

In an earlier email, on August 15, 2025, Lord Mandelson had told Mr McSweeney that a red box with Mr Trump's name and cypher 'fits the bill' for a gift.