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The first set of documents relating to the appointment of Lord Mandelson as theUK's ambassador to the US focused on the process of hiring and later firing the peer.

Ahead of today's expected release of a new tranche of files, we've taken a look back at the key takeaways from those documents:

"Reputational risk": Keir Starmer was advised that Mandelson's relationship with convicted sex offender Jeffrey Epstein posed a "general reputational risk" before his appointment as ambassador.

"Weirdly rushed": The prime minister's national security adviser, Jonathan Powell, had said in a "fact-finding call" he found the appointment of Lord Mandelson "weirdly rushed".

Severance package: The files suggested Mandelson requested a severance payment of £547,201 after he was sacked. The BBC understands he takes issue with this claim and insists he made it very clear he had no intention of taking his case to an employment tribunal. The Treasury ultimately agreed a payment of £75,000.

Ministers braced for private texts and WhatsApps in Mandelson file releasepublished at 13:33 BST

13:33 BST

Chris Mason and Henry Zeffman
Political editor and chief political correspondent

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The appointment of Peter Mandelson as the UK's ambassador to Washington is like a bad news boomerang for the government.

Over and over again the prime minister's most consequential judgement in office circles back into ministers' airspace – and today it will do so with gusto.

It will be "another one of those weeks" one senior figure said, wearily.

The scale of what is to come will be quite something: the largest government publication ever put before the Commons, and therefore us, other than the Chilcot Inquiry into the Iraq War – and that was a 12 volume, 2.6 million word affair.

It won't be on that scale, but it will run to over 1,000 pages. The first tranche, back in March, amounted to 147 pages.

Printed and bound, the publication will be made up of three volumes. More than 160 of the pages are made up of Lord Mandelson's text messages and WhatsApps.

In big picture terms, the documents will offer a fascinating internal insight, at scale, into how government works: the private interactions, information flows and disagreements.

• Read the analysis in full

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On 20 December 2024, Keir Starmer announced he would be appointing Peter Mandelson as the UK's ambassador to the US, saying he would bring "unrivalled experience to the role".

A specialist agency within the Cabinet Office then began the vetting process. It recommended Developed Vetting clearance be denied, but Mandelson was granted clearance by Foreign Office officials to become ambassador.

Here's a quick glance at what has unfolded since:

• 11 September 2025: Mandelson is sacked from his role following fresh revelations about the extent of his relationship with the late convicted sex offender Jeffrey Epstein
• 1 February 2026: Mandelson resigns from the Labour Party and steps down from the House of Lords
• 4 February 2026: MPs vote in favour of releasing documents relating to Mandelson's appointment
• 8 February 2026: Morgan McSweeney quits as Starmer's chief of staff after it's revealed he advised the PM to appoint Mandelson
• 23 February 2026: Mandelson is arrested on suspicion of misconduct in public office, then released. He remains under criminal investigation and has repeatedly let it be known that he believes he has not acted criminally, did not act for personal gain and is co-operating with police
• 11 March 2026: The first batch of files is released, showing Starmer was warned of the reputational risks before appointing Mandelson
• 16 April 2026: No 10 confirms Mandelson failed the vetting process and says Starmer was not made aware. The former head of the Foreign Office, Olly Robbins, is sacked
• 20 April 2026: Starmer tells MPs that if he had known Mandelson had failed vetting he would not have gone ahead with the appointment

• 28 April 2026: McSweeney says he made"a serious mistake" in recommending the appointment of Mandelson as the UK's ambassador to the US
• 31 April 2026: Three sources involved in the process of publishing the so-called Mandelson files tell the BBC the second tranche of documents will be published on 1 June
• Today: The prime minister's spokesman confirms the second batch of files will be released

Joe Pike
Political correspondent

Today's release of more than 1,000 pages of government documents is among the largest ever laid in Parliament.

Senior government sources have conceded the files will include details of text exchanges between ministers, advisers and Lord Mandelson which are embarrassing and cringeworthy.

We can expect to read details of the discussions around Mandelson's appointment as US ambassador, as well as an insight into his time as the UK’s man in Washington.

The document dump will contain emails, briefings and memos, as well as pages of messages on what seems to be the government’s preferred communications platform: WhatsApp.

Mandelson’s vetting file will not be included - it’s understood the Metropolitan Police have asked for it to be held back while they investigate him on suspicion of misconduct in public office. Mandelson has denied wrongdoing.

Other disclosures will be redacted on grounds of national security or international relations, such as private messages which could be critical of US President Donald Trump.

Iain Watson
Political correspondent

A little earlier, Downing Street said the second tranche of the so-called Mandelson files will be released around 14:30 BST.

Chief Secretary to the Prime Minister Darren Jones will be speaking in the Commons an hour later.

The PM's official spokesman says "every government department" was involved in meeting the terms of the humble address - the demand from Parliament to see documents related to Lord Mandelson’s appointment and time as the UK's ambassador to the US.

This is "the largest ever response to a humble address", the spokesman adds, which he says will provide "unprecedented" government transparency.

It has involved the discovery, assessment and analysis of "thousands of documents" and material of a party political nature will be included "in the interests of maximum transparency".

He also says there will be a clear explanation of how documents were gathered and any redactions made.

Some documents held back at the request of the police will be made available at a later date but the timing is not in the government’s hands.

Asked about disappearing messages in WhatsApp chats, he said there is a review of corporate communications channels.

The spokesman also says, when asked if a response is expected from Keir Starmer, that the PM has no "public facing commitments" today.

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A second set of documents relating to Peter Mandelson's appointment as the UK's ambassador to the US will be released today.

A government spokesperson says the release will provide "unprecedented government transparency". It will be made up of three volumes, running over 1,000 pages. More than 160 of those will include Lord Mandelson's text messages and WhatsApps.

Mandelson was sacked as ambassador in September 2025 after fresh revelations emerged about the extent of his relationship with the late convicted sex offender Jeffrey Epstein.

Back in February, MPs voted to force the government to publish all papers relating to his appointment through a humble address - a parliamentary mechanism used to force the government to disclose certain information.

The first tranche of documents, published in March, showed PM Keir Starmer was advised that Mandelson's relationship with Epstein posed a "general reputational risk".

Our team of writers and correspondents will bring you the latest developments and analysis over the next few hours - stick with us.