What is ‘DV’? Key terms used in the Mandelson vetting row explained

Peter Mandelson was sacked as the ambassador to the US in September last year. Photograph: Kin Cheung/APView image in fullscreenPeter Mandelson was sacked as the ambassador to the US in September last year. Photograph: Kin Cheung/APPeter MandelsonExplainerWhat is ‘DV’? Key terms used in the Mandelson vetting row explainedPhrases used by the UK’s national security apparatus have been thrown into the spotlight by the political controversyHenry Dyer and Jamie GriersonTue 28 Apr 2026 04.48 EDTFirst published on Mon 20 Apr 2026 09.15 EDTSharePrefer the Guardian on GoogleThe story of how Peter Mandelson failed his UK security vetting before he took up his post as ambassador to the US – and the overturning of the decision that he should not be given clearance – is full of the abbreviations of the British national security apparatus and the archaic language used to describe parliamentary process.Here are the key terms to understand about the story, as Morgan McSweeney and Philip Barton answer questions from the foreign affairs select committee. McSweeney, formerly Keir Starmer’s chief of staff, and the ex-Foreign Office chief Barton are giving evidence about who knew what, when.1. Developed vetting (DV)At the heart of the story is Mandelson’s application for a level of security clearance known as “developed vetting” (DV) made after his appointment as ambassador had been announced.According to a government guide to security clearance levels, officials in roles that require them to have “frequent and uncontrolled access” to top secret material and assets need to have DV. That could mean sensitive areas of government buildings as well as classified information.In the Foreign Office, it is routine for civil servants – including those in much more junior roles than Britain’s most high-profile diplomatic posting – to have DV clearance. To get DV, officials are subjected to personal and often quite intrusive interviews; they have to fill out questionnaires and provide referees who are asked about the character and history of the applicant.Security officials complete a form with three options: green, “clearance approved or remains valid”; yellow, “clearance approved or remains valid with risk management”, which might include later follow-up checks or restriction from working on certain policy areas; or red, “clearance denied or withdrawn”. In Mandelson’s case, they chose the third option to deny clearance.Politicians, however, are not vetted: it is deemed their democratic position gives them the right to access the sensitive materials necessary to fulfil their duties.2. United Kingdom Security Vetting (UKSV)For most civil servants, vetting processes are carried out by an agency, United Kingdom Security Vetting (UKSV). Those working in the intelligence community are vetted by the security and intelligence services, but the security services’ records are consulted as part of the UKSV process.UKSV is a part of the Cabinet Office, with offices in York. Some of its staff are former police officers, who use their experience to judge whether or not applicants are lying during their interviews.Given the probing nature of the questions – which, according to publicly available government documents, include queries on personal finances, business connections and sexual history – applicants are told that lying or hiding something they have done is more likely to lead to them failing the vetting process, rather than any judgment on their conduct.The reports…

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