McSweeney ‘asked if Mandelson US embassy role could be part-time’

Morgan McSweeney sought official advice over whether Peter Mandelson, who resigned from the Lords this week in disgrace, could be the UK’s ambassador to the US and chancellor of the University of Oxford at the same time, sources have claimed.

McSweeney, Keir Starmer’s chief of staff, is widely believed to have been the driving force behind the former Labour peer taking on the ambassador role after the pair worked together on the 2024 general election campaign.

At the time, in November 2024, Mandelson was also one of the frontrunners for the position of Oxford’s chancellor, the ceremonial head of the university. Senior government sources told The Observer that McSweeney asked Cabinet Office officials for advice as to whether Mandelson could carry out the two roles – based thousands of miles apart – simultaneously. McSweeney questioned whether the US ambassador role could be carried out on a part-time basis.

Officials “had to explain that being his majesty’s ambassador in Washington was a full-time job… in Washington”, said one person close to the matter. Another source said that the query was made at Mandelson’s behest.

The Washington-based position is the single most important role in maintaining the special relationship between the UK and US and held particular significance as a bridge between Starmer’s government and Donald Trump’s second presidency.

The Observer understands that Starmer was open-minded on whether the senior diplomatic role should be taken up by Mandelson or the Conservative former chancellor George Osborne, but that McSweeney was the one pushing Mandelson. Karen Pierce, the previous ambassador, was dismissed by Starmer despite winning praise for her work with both Joe Biden and Trump in his first presidency.

Last night the Metropolitan police confirmed a criminal investigation had been opened into allegations that Mandelson, a former business secretary, passed market-sensitive information to the paedophile financier Jeffrey Epstein. The allegations were made after the US Department of Justice released millions of documents relating to Epstein last week.

In the Commons today the Conservatives are planning to use a motion known as a “humble address” to force No 10 to release all communications from around the time Mandelson was appointed ambassador. The government has suggested an amendment to the motion to restrict the scale of the release and exclude documents that may be “prejudicial to UK national security or international relations”.

Mandelson’s appointment as ambassador was subject to two separate checks: the Cabinet Office compiled a dossier based on information that was already in the public domain, and the Foreign Office carried out what it calls deeper “developed vetting”.

The Cabinet Office’s dossier outlined Mandelson’s career – as well as his two previous resignations from cabinet positions while in government; his lobbying firm Global Counsel and its known client base, including Chinese firms; and his known links to Epstein, including that Mandelson had stayed at the financier’s apartment after the latter had been convicted and spent time in prison on charges of soliciting underage girls for prostitution. The details of the developed vetting process is typically kept secret, including from the subjects themselves.

Mandelson did not respond to requests for comment. The Cabinet Office declined to comment.

A government source said: “Peter thought he could do both roles. Morgan did not think he could.”

Photograph by Simon Dawson / No 10 Downing Street