On Monday the Cabinet Office is set to release the second batch of the Mandelson files, comprising over 1,000 pages of records on his appointment as UK ambassador to Washington. This disclosure will rank as the second-largest after the Chilcot inquiry report on the Iraq war and may prompt further scrutiny of Keir Starmer’s decision to appoint Peter Mandelson to the key diplomatic post. Ministers, officials and advisers were asked to provide WhatsApp messages and emails exchanged with Mandelson during his tenure, some of which could prove awkward and add pressure on the government. The material, obtained through the humble address process, excludes items deemed harmful to national security or international relations following review by the intelligence and security committee. Questions remain over whether embarrassing exchanges with ministers will appear, what items have been omitted, including a nine-page UKSV summary, and whether any written record exists of agreed security steps. Further uncertainty surrounds claims that Mandelson was viewed as a borderline case and the reasons behind the delayed review of the summary document in September 2025.
