Downing Street has set out how it will implement the Commons’ instruction to release papers on Lord Mandelson’s appointment as UK ambassador to the United States. In a formal letter dated 6 February 2026 to The Rt Hon the Lord Beamish, the Prime Minister confirms engagement with the Intelligence and Security Committee of Parliament (ISC) on sensitive material. (gov.uk)
The Prime Minister writes that the Cabinet Secretary will agree with the ISC the detail for sharing and reviewing information that could prejudice UK national security or international relations, taking account of requirements arising from a live Metropolitan Police investigation. The letter also says documents should be made available to Parliament “as soon as possible”, while noting the likely volume and the need to confirm scope. (assets.publishing.service.gov.uk)
On 4 February 2026 the House of Commons approved a Humble Address requiring the Government to lay before the House all papers relating to Lord Mandelson’s appointment, including Cabinet Office due diligence, conflict of interest returns, minutes and specified communications. An amendment agreed that papers prejudicial to national security or international relations should instead be referred to the ISC. Ministers told MPs the Government would comply and report back on progress. (hansard.parliament.uk)
Lord Beamish chairs the ISC, a statutory joint committee of Parliament. Under the Justice and Security Act 2013, departments and agencies must either provide information requested by the ISC in accordance with the memorandum of understanding, or a Secretary of State must formally decide not to disclose on limited grounds. (isc.independent.gov.uk)
Operationally, coordination now sits with the Cabinet Secretary, Sir Chris Wormald, who has served in the role since December 2024. His office will need to work across No 10, the Cabinet Office, the Foreign, Commonwealth and Development Office and UK Security Vetting to locate and triage material captured by the Commons motion. (gov.uk)
The handling of sensitive material is anchored in statute. The 2013 Act permits withholding from the ISC only where the Secretary of State judges the information both sensitive and, in the interests of national security, not disclosable to the ISC, or where it would be improper to produce it to a departmental select committee. Information received by the ISC in private is subject to publication restrictions, including consultation with the Prime Minister before release. (legislation.gov.uk)
During the debate, the Chair emphasised that the Metropolitan Police have no jurisdiction over how the House proceeds. The interface described in the Prime Minister’s letter is therefore administrative: the ISC will handle any sensitive papers while departments prepare material for laying before the House. (hansard.parliament.uk)
The Metropolitan Police investigation remains active. On 6 February, the Financial Times reported searches at properties linked to Lord Mandelson in Wiltshire and Camden as part of a misconduct in public office inquiry. This context explains the letter’s reference to aligning any document-sharing with investigative requirements. (ft.com)
Use of the Humble Address to obtain documents has become more frequent since 2017, including to secure Brexit analyses and security advice on peerages. In this instance, routing material that may damage national security or international relations via the ISC while laying other papers to the House reflects that evolving practice. (theguardian.com)
For departments, the immediate task is the disciplined retrieval of records within scope-emails, messages, minutes and due‑diligence files-followed by two parallel routes: public laying to the House for routine material, and secure ISC review for content that could prejudice national security or international relations. The Prime Minister says the Government will engage with the ISC “with the urgency and transparency it deserves”, with the Cabinet Secretary to follow up. (hansard.parliament.uk)