On Monday the Cabinet Office is expected to publish the second tranche of the Mandelson files – more than 1,000 pages of documents relating to his appointment as UK ambassador to Washington.
The document dump will be the second-largest to the House of Commons after the Chilcot inquiry report into the Iraq war, and its disclosures threaten to again raise awkward questions over Keir Starmer’s judgment in giving Peter Mandelson the UK’s most important diplomatic job.
Ministers, officials and advisers have all been required to disclose WhatsApp messages and emails with Mandelson during his time as ambassador, many of which threaten to be embarrassing at best – and could inflict yet more damage on Starmer’s embattled government.
The release, which was triggered by the humble address process, will not include information “prejudicial to UK national security or international relations”, after a redaction process carried out by the intelligence and security committee. We ask the main questions.
Will there be embarrassing messages between Mandelson and ministers?
The release of exchanges from his time in Washington could include criticism of the prime minister and awkward WhatsApp messages from ministers “trying to impress” the now former US ambassador. These could include group messages involving the former health secretary Wes Streeting, who has tried to distance himself from Mandelson. Government insiders have suggested there will also be messages revealing that Mandelson gave unsolicited advice to ministers on policy areas outside his diplomatic brief.
What has been left out of the document tranche?
What is not there could be as significant as what is. The documents to be released are understood not to include a nine-page summary document compiled by UK Security Vetting (UKSV). The Guardian disclosed last week that Mandelson’s associations with senior figures in China, Russia and Israel had been among the concerns raised by UKSV when it concluded he should be denied clearance – and these were all contained in the summary document. However, reports on Sunday suggested officials were no longer planning to release it after the Metropolitan police requested some documents not be made public.
What about the mitigations that were put in place?
Multiple sources have told the Guardian the documents contain no written record of what Mandelson and top security officials agreed would be necessary for him to receive security clearance for the job. Senior Foreign Office officials have told MPs that he agreed to take certain steps to allay concerns, but the lack of any written agreement casts doubt on those assurances. Some steps appear to have been taken to address commercial conflicts of interest caused by Mandelson’s stake in Global Counsel, the lobbying firm he co-founded. These management actions, however, were separate to security mitigations.
Will the documents confirm Mandelson was a borderline case?
Olly Robbins, the senior government official sacked for his role in appointing the former Labour minister after UKSV had recommended clearance be denied, told MPs the vetting body had “considered Mandelson a borderline case” and was only “leaning towards” recommending that his clearance should be denied. However, there have been no documents published so far that support the “borderline” claim – and the term has not been used by anyone else who has seen the UKSV documents. In fact, a template of the UKSV decision document suggests the exact opposite.
What happened in September 2025?
One prevailing mystery has been why Robbins and Ian Collard, the Foreign Office’s security chief, made their decision in late January 2025 without reviewing the summary document, doing so on the basis only of oral briefings about its contents. It was seven months later, when Mandelson was withdrawn from Washington, that they decided to review the summary document.
Robbins told MPs that queries had been made on his behalf about whether he could see the document – and that the Cabinet Office had said he needed a national security justification. However, the Cabinet Office’s top civil servant has said another request was made by the Foreign Office’s security team, which led to the summary document being handed over. Notes were apparently then taken of its contents by the security chief. It is unclear what triggered that action, and what the contents of the note were.
