Lord Peter Mandelson apparently “declined to comply” with a request to hand over his personal phone and allow the government to publish WhatsApp messages ahead of his appointment as US ambassador, documents reveal.
The Cabinet Office put forward a request on March 31 2026, to Mandelson, via his solicitors, to request any information held on his personal phone. The second tranche of files related to his appointment showed.
As Mandelson declined, the government had “no further recourse” to search his device.
In a handwritten note included in the files, Mandelson told the then Foreign Secretary, David Lammy, that the government would “never regret” his appointment as US ambassador.
He went on to say that it would be a “huge honour” to serve as ambassador to the US.
What do the files show?
- Mandelson said the government would “never regret” appointing him as ambassador to the US in a written note to David Lammy
- He “declined to comply” with a request to hand over his WhatsApp messages and other information on his personal phone to the government
- In an email, he said former transport secretary Louise Haigh’s exit from government was “harsh” after she quit over a fraud offence
- A Foreign Office Official said that Mandelson was given access to classified information before receiving full clearance
- Work and Pensions Secretary Pat McFadden shared criticisms of Starmer with Mandelson
- Concerns previously raised about Mandelson’s security clearance being rushed through are reinforced in these files.

A Foreign Office official told the Secret Intelligence Service (SIS) that Mandelson “is yet to receive his DV clearance”, but due to the timeframe of his appointment and his role as a Privy Counsellor, seniors gave Mandelson access to more classified material.
The vetting originally showed that Starmer’s appointment of Mandelson was a “reputational risk”, particularly relating to his links with Russia and China.
These files show that after his appointment was announced but before he actually started, Mandelson planned to take part in — and be paid for — a conference in Shanghai where he even asked to delay going onto government payroll to accommodate it.
WhatsApp messages between Mandelson and Work and Pensions Secretary Pat McFadden reveal heavy criticism of the prime minister’s leadership.
Mandelson told McFadden that the PM “is not leading from the front” and goes on to say that he believes things in Number 10 are “not good” and after a visit to Number 10 himself, Mandelson claims it “is beleaguered and bereft”.
Talking of unrest within the party, McFadden says Labour MPs are always asking “who can we tax in order to pay benefits to others” while also branding the welfare reforms as “very bad”.

Speaking in the Commons on Monday, Chief Secretary to the Prime Minister, Darren Jones, said the files are “one of the largest government publications ever laid before this House” and that the disclosure process has cost the Cabinet Office more than £1 million.
Jones defended the redacted material and said that any redactions in the material were those that may impact national security and that the remaining documents would be published “when the police are content for us to do so”.
MPs will be allowed to debate the release of files on Wednesday.
In February, MPs voted to demand ministers publish a range of documents relating to the appointment, using an archaic parliamentary process called a “humble address” following the launch of a police investigation into Lord Mandelson.
The first batch of files was released in March and included due diligence and advice provided to the prime minister, warning him of the “reputational risks” of appointing Mandelson to the role.
Mandelson was sacked in September 2025 following further revelations about his relationship with convicted paedophile Jeffrey Epstein, for which he had previously apologised, claiming he did not witness wrongdoing in his interactions with Epstein and “deeply regrets” continuing his relationship for so long.
Since then, he has been arrested on suspicion of misconduct in public office but denies the charges.
Downing Street indicated the release of documents was everything it planned to publish on Lord Mandelson, apart from files held back at the request of Scotland Yard to avoid jeopardising its investigation.
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