Mandelson scandal is so serious it could 'certainly bring down' Prime Minister, Labour MP tells LBC
The former Shadow Chancellor also blasted Mandelson's behaviour as "unforgivable"
Former Shadow Chancellor John McDonnell has told LBC that the Peter Mandelson scandal is so serious it could "certainly bring Keir Starmer down."
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The former Labour heavyweight compared the outrage to that caused by the Profumo affair in the 1960s, which saw the end of then-Prime Minister Harold Macmillan.
Speaking to LBC's Tonight with Andrew Marr, Mr McDonnell said: "The reality is this, you mentioned Profumo. It's as serious as that.
"This could bring this government down. It could certainly bring Keir Starmer down and this whole team around him, that's the seriousness of it."
Read more: Will Peter Mandelson be the final nail in Labour's coffin? Asks Andrew Marr
The comments came just hours after the Met Police confirmed a criminal investigation has been launched into Mandelson, amid allegations that he leaked market-sensitive information to Jeffrey Epstein.
In the latest release of the Epstein Files by the US Department of Justice, Mandelson was allegedly shown to pass material to Epstein while serving as business secretary in Gordon Brown’s Labour administration, as it dealt with the 2008 financial crash and its aftermath.
Mr McDonnell told Andrew it was "unforgivable" for Mandelson to be leaking information during the financial crisis, and admitted he was "shocked at the level of influence" he appeared to have.
The MP for Hayes and Harlington also said warnings sent to the Prime Minister in 2024 over Mandelson's appointment were ignored and overridden.
He added: "To give Gordon his due, he was holding things together as best he could in one of the biggest crises that we've seen.
"And here you have people just looking after self-interest and actually leaking stuff. That's unforgivable.
"You can see why the Labour MPs and others are so angry with him. It's an absolute betrayal."
Mandelson was appointed as the government's US Ambassador in December 2024, despite suggested links to Epstein at that point.
Mr McDonell added: "In 2024, when I heard he was to be appointed, I actually went public and I tweeted out saying I warned Keir.
"I couldn't believe it at that stage because we knew the connections at that stage with Epstein.
"So I was really shocked, and I spoke out at that time. But no one in Keir's team listened whatsoever.
"And the issue here is we need to know how is that decision made. Keir's obviously had advisors around him who've advised him on it. It looks as though they've overridden other advice that was coming in from elsewhere."
In a statement released on January 12 to Newsnight, Mandelson said: "I was wrong to believe him following his conviction and to continue my association with him afterwards.
"I apologise unequivocally for doing so to the women and girls who suffered."
Mandelson was removed from his role as US Ambassador in 2025 after the extent of his association with Epstein after the financier's release from jail for procuring a minor for prostitution was revealed.
He has previously said: "I was wrong to believe Epstein following his conviction [in 2008 for procuring a child for prostitution and of soliciting a prostitute] and to continue my association with him afterwards.
"I apologise unequivocally for doing so to the women and girls who suffered."
In an interview with The Times carried out last week but published on Monday, Mandelson referred to a "handful of misguided historical emails, which I deeply regret sending", and described Epstein as "muck that you can't get off your shoe".