Sir Keir Starmer backed Lord Mandelson in the House of Commons despite the Government already being aware of emails between him and paedophile Jeffrey Epstein, it emerged last night.

The Foreign Office was sent details of the exchanges early on Tuesday before passing them on to Downing Street, according to The Times.

Lord Mandelson was then backed by Sir Keir at Prime Minister’s Questions on Wednesday before he was dramatically sacked on Thursday as Britain’s ambassador to the US over emails revealing the peer offered support to Epstein even as he faced jail for sex offences.

There are fears that Lord Mandelson, who believes he was unfairly sacked, could be out for political revenge. It is believed that because the peer refused to resign, he could receive a substantial taxpayer-funded payout. He is still on the Government payroll and will be paid until a settlement is reached.

It comes as Labour MPs angrily rounded on Sir Keir and his most senior adviser last night amid a fractious blame game over Lord Mandelson’s exit.