Additional files concerning Lord Peter Mandelson's tenure as the UK's ambassador to the US are slated for release before the parliamentary recess in December. The Cabinet Office announced that certain documents, previously withheld to avoid prejudicing a Metropolitan Police investigation, can now be published.
Batches of papers were released earlier this year after MPs invoked a parliamentary procedure known as a 'humble address.' However, some files remained undisclosed due to their potential impact on the police probe into allegations that Lord Mandelson passed market-sensitive government information to the late convicted sex offender Jeffrey Epstein.
Cat Little, permanent secretary to the Cabinet Office, stated in a letter to Lord Beamish, chair of Parliament's Intelligence and Security Committee (ISC), that the Metropolitan Police have assessed that a number of these documents can be published without prejudice to their ongoing investigation. The Cabinet Office is now preparing these documents for submission to the House.
These documents will undergo review for potential redactions related to national security or international relations, which would then be referred to the ISC. Members of the ISC will have access to unredacted versions before wider publication.
Some documents will continue to be withheld at the request of the Metropolitan Police if they could risk compromising the ongoing investigation or any subsequent legal proceedings. A police spokesperson confirmed the investigation into alleged misconduct in public office is active.
Lord Mandelson was appointed UK ambassador to Washington in February 2025. His tenure ended in September 2025 when he was dismissed by then-Prime Minister Sir Keir Starmer following the leak of supportive messages sent by Mandelson to Epstein. Earlier releases of documents included admissions from an official involved in security clearance that they did not fully understand the Strap enhanced clearance system, and suggested a peer might be exempt from certain requirements.
In a 2025 message to Cabinet minister Pat McFadden, Lord Mandelson reportedly commented that Sir Keir 'lacks verve as does the Cabinet as a whole.'