Morgan McSweeney, former top aide to UK Prime Minister Keir Starmer, told MPs on Wednesday that learning about Peter Mandelson's close ties to convicted sex offender Jeffrey Epstein felt like "a knife through my soul" and that the decision to appoint Mandelson as US ambassador was "wrong."
Appearing before the Foreign Affairs Committee, McSweeney provided a dramatic account of how the revelation emerged, describing his shock and dismay. He said the appointment should not have gone ahead given the nature of Mandelson's relationship with Epstein.
The testimony comes as the UK government faces continued scrutiny over the Mandelson nomination, which has drawn criticism from both opposition parties and some within Labour.
McSweeney, who served as Starmer's chief of staff until recently, did not hold back in his assessment, calling the decision a serious misjudgment. His remarks are likely to intensify pressure on Starmer to explain how the appointment process unfolded.
The committee is investigating the circumstances surrounding Mandelson's selection for the key diplomatic post in Washington.