Starmer’s chief of staff resigns after admitting fault in Mandelson’s US ambassador appointment

A week of escalating political turmoil at the heart of the British government reached a dramatic climax on Sunday when the prime minister’s chief of staff resigned over the scandal surrounding the appointment of Peter Mandelson as the United Kingdom’s ambassador to the United States.

Morgan McSweeney, the most senior political adviser to Prime Minister Keir Starmer, stepped down after sustained pressure over Mandelson’s role and his past association with disgraced financier and convicted sex offender Jeffrey Epstein. In a stark statement, McSweeney accepted full responsibility for advising Starmer to proceed with the appointment, calling the decision a serious mistake that had damaged public trust.

“The decision to appoint Peter Mandelson was wrong,” McSweeney said. “He has damaged our party, our country and trust in politics itself. In the circumstances, the only honourable course is to step aside.”

The resignation marks one of the most severe blows yet to Starmer’s premiership and underscores the scale of the crisis engulfing his government. McSweeney, a key architect of Labour’s landslide election victory, had been one of Starmer’s closest and most influential allies inside Downing Street.

Although McSweeney said he did not personally oversee the vetting and due diligence process for Mandelson’s appointment, he acknowledged that the safeguards in place had failed. He called for a fundamental overhaul of the system used to assess candidates for senior public roles, warning that reform must go beyond symbolic gestures.

Starmer responded swiftly, thanking McSweeney for his service and praising his role in securing Labour’s return to power. In a statement, the prime minister said McSweeney’s “dedication, loyalty and leadership” had been instrumental in delivering a decisive election win and the chance to reshape the country. However, the tribute did little to quell mounting concerns about Starmer’s own judgement.

The controversy intensified following the release of a new tranche of files by the United States Justice Department relating to Epstein. The documents prompted British police to open a criminal investigation into Mandelson, who stands accused of sharing confidential and market sensitive government information that would have been of financial interest to Epstein after the 2008 financial crisis.

As part of the investigation, officers raided two properties linked to Mandelson on Friday. The former cabinet minister has already resigned from the Labour Party and stepped down from the House of Lords, further fuelling the sense of a rapid and humiliating downfall for one of the party’s most prominent figures.

Mandelson’s friendship with Epstein, which continued even after Epstein’s 2008 conviction for soliciting prostitution from an underage girl, had long been a matter of public record. Critics have questioned why this relationship did not automatically disqualify him from representing Britain in Washington.

The scandal has exposed deep unease within Labour ranks and raised uncomfortable questions about accountability at the very top of government. Opposition figures and some Labour MPs have accused Starmer of failing to act sooner, arguing that the damage could have been contained had stronger action been taken when Mandelson’s background was first scrutinized.

For Starmer, the resignation of his chief of staff represents a pivotal moment. With police investigations ongoing and political pressure unrelenting, the affair has cast a long shadow over his leadership and his promise to restore integrity to public life.

As Downing Street attempts to stabilize, the episode stands as a stark reminder of how swiftly unresolved associations and flawed appointments can spiral into a full-blown political crisis.