The British government has been plunged into a profound crisis following the revelation by the Guardian that Peter Mandelson, appointed as British ambassador to Washington, failed his security vetting checks in January 2025. This news sent shockwaves across Keir Starmer’s cabinet, with key ministers expressing surprise and a lack of prior knowledge about the vetting process.

Chancellor Rachel Reeves, in Washington for the IMF spring meeting, stated her ignorance of the vetting, emphasizing her role as chancellor, not foreign secretary or 10 Downing Street. Deputy Prime Minister David Lammy, alerted mid-flight from the Middle East, also confirmed he was unaware, despite having been foreign secretary at the time. Current Foreign Secretary Yvette Cooper reacted with "pure, unbelievable shock" upon learning the news, while Prime Minister's chief secretary Darren Jones was urgently summoned back to London.

The common sense of astonishment among senior government figures underscored how few were privy to the fact that Mandelson’s appointment was made against the explicit advice of senior security officials. Downing Street initially insisted that no minister, including the prime minister, knew about it at the time. The exact sequence of events, both leading up to the appointment and in the days following the revelation, is set to be scrutinized in the coming weeks, potentially determining the future of the British prime minister.

The saga began in January 2025, when Keir Starmer announced Mandelson as his controversial choice for the crucial diplomatic post of British ambassador in Washington, dubbed the UK’s "Trump-whisperer." Mandelson’s suitability was questioned due to his post-ministerial career, during which he founded a lobbying firm, Global Counsel, with clients linked to China, raising conflict of interest concerns. His public relationship with convicted child sex offender Jeffrey Epstein was also a known factor at the time of his appointment.

Despite his chequered past and the significant questions regarding his suitability, the Foreign Office and Starmer may have anticipated a straightforward vetting process. However, the UK Security Vetting (UKSV), a division of the Cabinet Office responsible for background checks, conducted a developed vetting (DV) process. This rigorous procedure involves questionnaires and interviews demanding disclosure of highly private information, including finances, business connections, and sexual history, with input from security services. By January 28, 2025, UKSV had made its decision: Mandelson was denied clearance, citing a "high" overall concern, a rare outcome for Foreign Office officials.

In a contentious move, senior officials at the Foreign Office decided to override the UKSV’s security advice and grant Mandelson security clearance anyway, employing a rarely used authority. Downing Street claimed this decision was made internally within the department, without the prime minister’s team being aware. Keir Starmer, visibly furious, told reporters on Friday that it was "unforgivable" that he was not informed of Mandelson's vetting failure, especially as he had repeatedly told parliament that "full due process" had been followed and that security vetting had "given [Mandelson] clearance."

If Starmer’s account is accurate, it implies that senior Foreign Office officials took the extraordinary step of disregarding security advice without informing any senior politician or the prime minister’s advisers. If his claims are untrue, Starmer faces accusations of deliberately misleading MPs and the public. While some parliamentary colleagues doubt his version, many believe him, yet remain unimpressed, viewing the incident as emblematic of his perceived lack of political acumen and "incuriosity" in sensitive matters.

The prime minister's aides stated that Starmer was first notified of Mandelson’s failed security check earlier this week when Cabinet Office officials discovered documents relating to the vetting process while preparing papers for MPs. No 10 immediately informed Starmer, who called an urgent meeting with top civil servants, including Antonia Romeo (the most senior civil servant), Catherine Little (Cabinet Office head), and his chief of staff Vidhya Alakeson. Starmer, reportedly furious, tasked them with uncovering the full facts.

However, Starmer did not immediately disclose this information. During Prime Minister’s Questions the following day, which focused on defence spending, no mention was made of the Mandelson vetting process. Darren Jones explained that the prime minister had not raised the issue as he was still gathering facts, to avoid inadvertently making a mistake in parliament. Allies of Starmer indicated his anger that officials had not informed him at earlier, opportune moments, such as when the US Department of Justice released the Epstein files.

Soon after the Downing Street meeting, Starmer sacked Sir Olly Robbins, the most senior civil servant in the Foreign Office. Robbins, who was permanent under-secretary until 2020, has been publicly defended by his predecessor, Simon McDonald, who accused Starmer of "throwing him under a bus." McDonald argued that No 10 "required a scalp and wanted it quickly," without affording Robbins any due process or fairness. McDonald stated that this situation marks the "biggest crisis in the diplomatic service" since 1982.

Robbins is expected to testify before the Commons foreign affairs select committee next week, a session anticipated to be highly critical and potentially damaging for Starmer. McDonald suggested that the government misrepresented the vetting process to shift blame, asserting that the decision to appoint Mandelson, despite civil service concerns, was ultimately made by the prime minister, who "wanted his man to go to Washington."

Further revelations intensified the crisis: Cabinet Secretary Antonia Romeo and Cabinet Office Permanent Secretary Catherine Little had known about Mandelson’s vetting failure for weeks, since late March, but did not immediately inform the prime minister. They sought legal advice regarding potential prejudice to a Metropolitan Police investigation and queried the Foreign Office’s decision to grant clearance against advice. Despite up to a dozen officials being aware, the PM reportedly remained uninformed until Tuesday, having previously denied a Mail on Sunday inquiry about the vetting failure in September.

The political fallout is severe, with leaders of major opposition parties, including Conservative leader Kemi Badenoch, calling for Starmer’s investigation or resignation, accusing him of lying or gross incompetence. Within the Labour party, MPs are reportedly in a "febrile mood" amidst repeated scandals and anticipated heavy losses in upcoming local elections. YouGov polling indicates only 16% of Britons believe the prime minister has been honest about the ambassadorship decision, while 53% believe otherwise.

The debate also extends to the confidentiality of security vetting. McDonald emphasized that vetting is a confidential process, with details closely held and typically not shared with No 10 or the prime minister unless a "black and white" failure occurs. He suggested Mandelson’s case was "more complicated" than No 10 presented, involving judgment and mitigation rather than a clear-cut failure, and that Robbins, in maintaining confidentiality, was "following the rules and applying his judgment as far as I can see." Starmer faces two critical parliamentary sessions next week: his own statement to the Commons on Monday and Robbins’ testimony on Tuesday, which could ultimately determine his political survival.