Barton and McSweeney face questions over Mandelson US ambassador appointment process

Senior civil servants have faced questions about the controversial appointment of Lord Mandelson as UK Ambassador to the United States, with evidence revealing pressure from Number 10 to expedite the vetting process and concerns about his Epstein connections.

The parliamentary committee heard from Barton, a former FCDO official, and McSweeney, a political advisor to the prime minister, about the circumstances surrounding Mandelson's appointment.

Barton said there was "absolutely" pressure on the Foreign, Commonwealth and Development Office to get Mandelson to Washington as quickly as possible, ideally before Trump's inauguration. He said Number 10 was "uninterested" in the vetting process, with inquiries focused on the pace at which he could arrive.

McSweeney confirmed he advised the prime minister to appoint Mandelson, stating: "I advised the prime minister in support of that appointment and I was wrong to do so." He described it as "a serious error of judgment."

Both officials revealed they had concerns about Mandelson's friendship with Jeffrey Epstein. McSweeney said he put his concerns in writing and received a reply, though he accepted Mandelson's version that they were not close friends. The email is now being withheld by the Met Police as part of their investigations.

"What emerged since then was way, way, way worse than I had expected at the time," McSweeney said. "When I saw the pictures, when I saw the Bloomberg revelations in September 2025, I have to say it was like a knife through my soul."

Barton said he was well aware of the "toxic" nature of the Epstein connection from his time in the US, though he only knew what was in the public domain at the time.

Both officials denied knowing that Mandelson had failed the UK Security Vetting process. McSweeney said Number 10 "didn't have a contingency plan" but was always aware vetting could fail.

The committee also heard that the rumour McSweeney had called Barton telling him "just fucking approve it" was untrue. Barton said he had never spoken to McSweeney apart from in group meetings and that McSweeney had never sworn.

McSweeney admitted it had not been ideal for him and Labour's communications chief Matthew Doyle to be the ones making inquiries to Mandelson about Epstein, saying: "When I look back on it, I certainly think it would have been much, much better if I'd asked PET to ask those follow-up questions."

Barton stepped down on Sunday 19 January, with the privileges committee vote on referral underway in the Commons.