Keir Starmer could be forced to reveal confidential vetting documents from Peter Mandelson’s appointment as US ambassador, with the Tories set to trigger an extraordinary Commons vote to force their release.
Labor MPs have indicated they are not prepared to oppose a Conservative motion – known as a humble address – which would reveal details of the vetting process and what is known about Mandelson’s links to disgraced financier Jeffrey Epstein.
Kemi Badenoch plans to use arcane parliamentary procedures on Wednesday to force the release of files related to the appointment of Mandelson as UK ambassador to the US.
In a dramatic move that will put pressure on Starmer’s chief of staff Morgan McSweeney, Badenoch said he would use the procedure to find out “why proper vetting didn’t happen”.
Badenoch is expected to say Labor MPs have a choice to “support our efforts to reveal the truth about how and why Peter Mandelson was appointed ambassador to Washington despite his known links to pedophile Jeffrey Epstein” or to help Starmer and McSweeney “avoid investigating this nefarious affair”.
A fast-paced day in Westminster ended with the Metropolitan police launching a criminal investigation into allegations that Mandelson leaked Downing Street emails and market-sensitive information to convicted sex offender Epstein.
A humble address, the same mechanism that forced the release of key Brexit papers, requires the government to release all communications related to Mandelson’s appointment including emails, WhatsApp messages and texts.
The rarely used parliamentary device could lead to the release of communications from Starmer, McSweeney and senior Foreign Office official Oliver Robbins, and reveal how much ministers knew of the risks of appointing Mandelson. The Conservatives will argue that McSweeney was “deeply implicated” in the scandal, which is reported to have pushed hard for No 10 for his appointment.
Badenoch also called on the cabinet secretary, Chris Wormald, to probe the justice secretary, David Lammy, and the work and pensions secretary, Pat McFadden, about any information they might have about Mandelson’s behavior as business secretary when they were junior ministers in his department.
The humble speech will demand the immediate publication of the due diligence process forwarded by No 10 from the Cabinet Office, the Conflict of Interest form provided by Mandelson to the Foreign, Commonwealth and Development Office, and material provided by the UK security vetting including documents about Global Counsel, the advisory firm he founded in 2010.
It will also include minutes of meetings, digital communications and all “information provided by the prime minister prior to his assurance in this house on 10 September 2025 that the entire process has been followed in this appointment, as with all ambassadors”, said a Conservative spokesman.
Starmer told a cabinet meeting on Tuesday morning that she was shocked by the reported leaks, and Downing Street officials confirmed that ministers had given a dossier on Mandelson to the police.
By Tuesday afternoon the former business secretary had resigned from the House of Lords but the government was under increasing pressure to publicly scrutinize the vetting process before Mandelson was appointed US ambassador – to find out the extent of the role McSweeney played in the process.
It is understood that the foreign affairs committee discussed whether McSweeney could be called to give evidence on the appointment but no decision was made, and it is believed that as a special adviser he may refuse to appear.
Labor MPs privately called on Tuesday for the Conservatives to use their opposition day debate on Wednesday to use the humbling address to force disclosure of the documents.
“There is certainly a lot of pressure and colleagues are voicing concerns, especially I gathered what No 10 said when Mandelson was appointed,” said one MP.
“It is clear from the letter that was made public to Mandelson asking him to disclose the hours he was at Epstein’s house that there is a different excitement from No 10 about the extent of this relationship and what else could be there,” one added. A third MP said it was “obviously they were just giving him the chance to excuse himself” and called it a “botch job”.
MPs said they did not believe the Labor whips office would be able to ask them to vote against a Tory motion related to Mandelson. “No one is willing to go through the lobbies to oppose that,” said one MP.
A former minister said he was clearly more aware of the potential leak of confidential information because Gordon Brown said he raised it with the Cabinet Office before sacking Mandelson as ambassador. They said: “At every step I think we are not being told the whole story.”
Another said: “There is a casualness to the way these emails are being forwarded.
They said they were particularly concerned about Mandelson’s contact with US tech firm Palantir, which has secured government contracts and which Starmer recently visited in Washington DC.