Morgan McSweeney, the former chief of staff to Sir Keir Starmer, emerged from the shadows on Tuesday to take full responsibility for the controversial appointment of Peter Mandelson as US ambassador. In four hours of testimony before Parliament's foreign affairs committee, McSweeney admitted it was a 'serious error of judgment' and said he resigned because accountability must not be selective.
McSweeney takes the blame
Opening with a brief personal statement, McSweeney sought to shift blame away from the Prime Minister. 'The appointment of Mandelson as ambassador was a serious error of judgment,' he stated. 'I advised the Prime Minister in support of that appointment and I was wrong to do so. As I said in my resignation statement, I resigned because I believe responsibility should rest with those who make serious mistakes. Accountability in public life cannot apply only when it is convenient.' He added: 'The Prime Minister relied on my advice and I got it wrong.'
The secret meeting
It emerged that Sir Keir made the decision to pick Mandelson at a meeting on or around December 15, 2024, days before the public announcement. Attendees included national security adviser Jonathan Powell and the Prime Minister's private secretary Nin Pandit. MPs were told the four debated the pros and cons before the decision was made.
Did Mandelson tell the truth?
The Prime Minister asked McSweeney to quiz Mandelson on his friendship with Jeffrey Epstein after due diligence documents warned they were 'particularly close'. McSweeney initially suggested he did not fully believe him, saying: 'I didn't feel that I got (the truth) back from him. But it wasn't my decision. It was the Prime Minister's decision and he saw the DV as part of that decision.' However, he later said he 'thought he had told the truth' and would never have allowed the appointment if he suspected Mandelson was lying.
Knife through soul
Describing his horror when Bloomberg revealed in September 2025 that Mandelson had told Epstein 'I think the world of you' just before the paedophile was jailed, McSweeney said: 'It was like a knife through my soul. The truth was way, way, way worse than I had expected at the time.'
Second thoughts
McSweeney suggested some ministers and officials are rewriting history by claiming they warned against Mandelson. He said: 'If everyone else was opposed to this appointment but me, (Sir Keir) would not have made it.' But he added: 'I could see that there were pros and cons in the appointment and I worried it would go wrong, so I didn't try to push anything through.'
No vetting concerns
McSweeney admitted it would have been 'very embarrassing' if Mandelson had failed his vetting after being appointed, but said there was 'no Plan B'. Despite well-known concerns about Mandelson's links to Epstein, China and Russia, the question of whether he would pass vetting 'did not jump out to me as a problem'.
Why choose him?
The former chief of staff said the idea of appointing Mandelson to Washington was first suggested 'by Mandelson himself'. Sir Keir decided in opposition he wanted a political appointee but waited until after the 2024 US presidential election. Due diligence was carried out on both Mandelson and former Tory chancellor George Osborne, with Mandelson winning approval due to his trade negotiation experience.
Not my hero
McSweeney denied reports he was in thrall to Mandelson. He acknowledged growing close to the New Labour grandee but said he did not regularly seek his advice until 2021. 'I didn't regard him as my mentor,' he added, and denied claims Mandelson was his 'hero'.
Other ambassador role
Downing Street tried to find an ambassadorial role for ex-Labour spin chief Matthew Doyle, McSweeney revealed. But he denied this amounted to 'jobs for the boys', saying it was good management for Sir Keir to find a 'softer landing'.
The missing phone
McSweeney denied deliberately giving police the wrong address when his mobile phone was snatched in the street last October. 'I was adrenalised, and if I gave any wrong direction, it wasn't intentional,' he said. The theft has raised fears that messages about Mandelson's appointment may be lost, but McSweeney suggested they were handed to No 10.
Fait accompli
In an earlier session, former Foreign Office mandarin Sir Philip Barton revealed he was not consulted on Mandelson's selection. 'At no point did anyone consult me, ask me. I was presented with a decision and told to get on with it,' he said, admitting he was 'worried'.
There was pressure
Sir Philip agreed with other Foreign Office figures that there was pressure to process Mandelson's clearance quickly, though not 'on the substance' of the DV decision. There were demands from No 10 to get the ambassador in place rapidly.
'Fit and proper person'
The Cabinet Office initially claimed that because Mandelson was a peer, he was classed as a 'fit and proper person' and did not require DV. Sir Philip said he raised concerns and the Cabinet Office eventually backed down.
Not normal process
In another blow to Sir Keir's claim that due process was followed, Sir Philip said the 'normal order' in ambassadorial appointments is 'vetting then announcement'. In Mandelson's case, the timing was 'driven and decided by No 10'.
Lammy's worries
Sir Philip also confirmed that then-foreign secretary David Lammy shared his concerns, telling him 'he would talk to No 10' at the time.
