The Prime Minister is under growing pressure after a top civil servant was effectively fired in the row over Peter Mandelson’s appointment as US Ambassador.

Sir Keir is said to be “furious” after only learning this week the Foreign Office overruled a recommendation by security experts not to clear former Hartlepool MP Lord Mandelson to become UK ambassador to the US.

It was announced on Thursday night that Olly Richards, the Foreign Office's top civil servant, will be leaving his post over the vetting decision.

The PM’s right hand man, Chief Secretary Darren Jones, told BBC Breakfast on Friday that Keir Starmer had not mislead Parliament over the appointment when he said due process had been followed throughout, and has not considered resigning.

The Prime Minister and Peter Mandelson pictured together last year. Photo: Carl Court/PA Wire

placeholder image — The Prime Minister and Peter Mandelson pictured together last year. Photo: Carl Court/PA Wire

Mr Jones said: “The fact that due process involved the right for the Foreign Office to ignore the recommendation of the security vetting team is astonishing.”

But Leader of the Opposition Kemi Badenoch has accused the Prime Minister of "deliberate dishonesty" over his handling of Lord Mandelson's appointment as US ambassador and called on him to resign.

She said: "It is utterly preposterous that throughout this period the Prime Minister did not know that Mandelson failed his security vetting, and (after) all the questions that we've been asking over the last seven months, that he, the chief prosecutor, didn't ask what happened with the security vetting – it just doesn't add up."

Mandelson was sacked from his Washington role last September when more details emerged about his relationship with paedophile financier Jeffrey Epstein, who died in 2019.

Sir Keir will face MPs on Monday.