Keir Starmer could be forced to disclose confidential vetting documents from Peter Mandelson’s appointment as US ambassador, with the Tories set to trigger a rare Commons vote to compel their release.
Labour MPs have indicated they are not prepared to oppose the Conservative motion – known as a humble address – that would disclose the details of the vetting process and what if anything was known about Mandelson’s links to the disgraced financier Jeffrey Epstein.
Kemi Badenoch plans to use the arcane parliamentary procedure on Wednesday to force the release of files relating to the appointment of Mandelson as the UK’s ambassador to the US.
In a dramatic move that will put pressure on Starmer’s chief of staff Morgan McSweeney, Badenoch said she would use the procedure to uncover “why the proper vetting never happened”.
Badenoch is expected to say that Labour 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 the paedophile Jeffrey Epstein” or to help Starmer and McSweeney “dodge scrutiny over this sordid affair”.
A fast-moving day in Westminster concluded 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, would require 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 to what extent ministers were aware of the risks of appointing Mandelson. The Conservatives will argue that McSweeney was “deeply implicated” in the scandal, having reportedly pushed hard within No 10 for his appointment.
Badenoch also called on the cabinet secretary, Chris Wormald, to quiz the justice secretary, David Lammy, and the work and pensions secretary, Pat McFadden, about any information they may have had about Mandelson’s behaviour as business secretary when they were junior ministers in his department.
The humble address will demand the immediate publication of the due diligence process passed on to No 10 from the Cabinet Office, the Conflict of Interest form Mandelson provided to the Foreign, Commonwealth and Development Office, and material given to UK security vetting including documents about Global Counsel, the advisory firm he co-founded in 2010.
It would also include minutes of meetings, digital communications and all “information provided to the prime minister prior to his assurance to this house on 10 September 2025 that full due process was followed during this appointment, as it is with all ambassadors”, said a Conservative spokesperson.
Starmer told a meeting of the cabinet on Tuesday morning he was appalled by the reported leaks, and Downing Street officials confirmed that ministers had handed 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 coming under increasing pressure to publicly examine the vetting process before Mandelson was appointed US ambassador – to determine the extent of the role that 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 could refuse to appear.
Labour MPs were privately clamouring on Tuesday for the Conservatives to use their opposition day debate on Wednesday to use the humble address to force disclosures of documents.
“There’s definitely a lot of pressure and colleagues making concerns known, especially I gather around what No 10 was told when Mandelson was appointed,” one MP said.
“It is clear from the letter that was made public to Mandelson asking him to disclose the times he was at Epstein’s home that there was a distinct incuriosity from No 10 about the extent of this relationship and what more could be out there,” another added. A third MP said it was “clear they just gave him the opportunity to excuse himself” and called it a “botch job”.
MPs said they did not believe the Labour whips office would be able to ask them to vote against a Tory motion related to Mandelson. “No colleague would be prepared to go through the lobbies to oppose that,” one MP said.
One former minister said it was clear more was known about the potential leaking of confidential information because Gordon Brown said he had raised it with the Cabinet Office just before Mandelson was sacked as ambassador. They said: “At each step I don’t think we’re being told the full story.”
Another said: “There was a casualness to the way these emails are forwarded. We should be told what contacts he had as ambassador.”
They said they were particularly concerned about Mandelson’s contact with the US tech firm Palantir, which has secured government contracts and which Starmer visited when last in Washington DC.
