Government prepares huge release of Mandelson appointment files to Parliament

The real test in the next release of Peter Mandelson’s appointment papers is not how many pages land in Parliament, but whether they change the story. MPs and the public will be watching to see if the second tranche sheds new light on Mandelson’s role, exposes gaps in earlier disclosures, or simply buries a politically explosive episode under sheer volume.

Darren Jones told the House of Commons on 19 May that the government had already referred more than 300 documents to the Intelligence and Security Committee, and said the next batch would be published after Whitsun recess so members had time to review it. A government spokesperson said the files “will be among the largest publications ever laid in Parliament”, underlining the scale of the release and the pressure on the Cabinet Office to show it has not slowed disclosure to protect itself.

The material is being released because of a Humble Address agreed by the House on 4 February 2026, which forced the government to hand over papers connected to Mandelson’s appointment as UK ambassador to the US. That order has already produced one tranche in March, which reportedly included details of a £75,000 severance payment. The next batch is expected to contain more sensitive material from across government, including records tied to UK Security Vetting, the Foreign Office and Downing Street.

The most contentious item is a nine-page summary of Mandelson’s security vetting. Reports on 31 May said police had asked the Cabinet Office not to publish some documents because they could affect an ongoing Metropolitan Police investigation and any future prosecution. That has put the government in a narrow position: it says it must comply with the Humble Address in full, while also protecting national security, international relations and the duty of care owed to junior staff.

The dispute has reopened the most damaging questions around Mandelson’s posting to Washington. Earlier reporting indicated that UK security vetting had recommended against granting him clearance, and Mandelson was later sacked in September 2025 after emails emerged showing he urged Jeffrey Epstein to “fight for early release”. Sir Jeremy Wright, Lord Beamish and Sir John Hayes are among the MPs with reason to press for a fuller account of how the appointment was approved and who knew what, and when.

For Parliament, the danger is that the second tranche becomes a test not just of disclosure, but of whether the state can explain itself without hiding behind volume, delay or selective redaction.