Senior figures in Sir Keir Starmer’s government are preparing to hand over tranches of their electronic communications with Lord Mandelson ahead of the release of evidence about his appointment as US ambassador.
The deepening scandal prompted an apology on Wednesday from Sir Keir to the victims of Jeffrey Epstein for believing Lord Mandelson’s “lies” and appointing him when the peer’s friendship with the paedophile was already public knowledge.
Despite the prime minister’s attempt to defuse the row, some of his own MPs are calling on him to stand down.
It comes as No 10’s former communications director warned the disclosure of private messages could drag more public figures into the scandal.
“I don’t think anyone can understate the gravity of the situation,” James Lyons told BBC Newsnight.
He said Wednesday’s approval of the release of documents about Lord Mandelson’s appointment meant “we could just be in the foothills here”.
“We’ve seen with the Covid inquiry how a huge amount of stuff can be thrown up through that.
“I think this is at least the biggest scandal since the expenses scandal of 2009.”
The BBC understands Lord Mandelson’s view is that he answered questions about his relationship with Epstein in the vetting process accurately.
Sir Keir has promised to release files, which he says will prove Lord Mandelson lied about the extent of his friendship with Epstein when he was being vetted for the ambassador role.
Any documents the government deems potentially unfit for the public eye will go to Parliament’s Intelligence and Security Committee for further scrutiny.
That committee has said it expects the government to provide all documents within scope of that process – which would include personal exchanges between government figures and Lord Mandelson stretching back to Labour’s election victory.
The committee added it expects the documents will be laid before parliament “very shortly”.
If the documents published cause any further embarrassment for the government over what was known about Lord Mandelson and Epstein’s relationship, it would likely lead to yet another difficult moment for the prime minister.
On Wednesday Sir Keir began a planned speech on funding to improve local communities by addressing the growing anger over how he had dealt with the issue.
While he acknowledged it had been publicly known for some time that Lord Mandelson knew Epstein, he said: “None of us knew the depths and the darkness of that relationship.”
Directly addressing Epstein’s victims, he said: “I am sorry, sorry for what was done to you, sorry that so many people with power failed you. Sorry for having believed Mandelson’s lies and appointed him and sorry that even now you’re forced to watch this story unfold in public once again.”
Conservative leader Kemi Badenoch said the PM’s position was “untenable”, while the Liberal Democrats called for a confidence vote to see if Labour MPs supported him.
