Keir Starmer faces fresh scrutiny today over the Mandelson vetting scandal as the mandarin he sacked is grilled by MPs over the affair.

Sir Olly Robbins, the former most senior civil servant in the Foreign Office, will appear in front of the foreign affairs select committee.

Former colleagues yesterday said he had endured an ‘utterly rough few days’ and was ‘heartbroken’ at his sacking.

When he gives evidence today, he is expected to maintain that he did nothing wrong in overruling security concerns about Lord Mandelson’s appointment as US Ambassador in December 2024.

Sir Olly was dismissed by a ‘furious’ Sir Keir last week over claims the civil servant had kept him in the dark about concerns surrounding Mandelson.

As Theresa May‘s former Brexit adviser, Sir Olly has had a long career in Whitehall and is highly regarded by colleagues with the backing of fellow civil servants.

He is likely to be asked why he didn’t make the vetting recommendations known to ministers and other civil servants. Sir Olly is set to maintain that he was bound by the law from sharing details about security vetting with ministers.

His allies have briefed that he could not disclose the information under the Constitutional Reform and Governance Act 2010. However, the Government published a legal opinion which says that there was nothing to prevent civil servants from ‘flagging’ the vetting recommendations.

Sir Olly is also likely to contend that the concerns noted in the vetting process were well known to the Prime Minister when he appointed Lord Mandelson.

The ex-US Ambassador’s links to convicted paedophile Jeffrey Epstein plus details of his business interests in Russia and China were well documented. After being appointed to the job after the announcement was made, he is likely to maintain he was simply carrying out the PM’s wishes.

He is likely to argue that Sir Keir had already made clear his intention to appoint Lord Mandelson despite knowing the risks.

But he will be accused of misleading the committee after failing to inform them about whether any ‘red flags’ were raised about Lord Mandelson’s appointment.

Last week, committee chairman Emily Thornberry said: ‘Looking at the evidence that was given and the letters that have been written, to be charitable, there are glaring holes.

‘It really is a question of whether we were knowingly misled.’

Sir Olly will also be asked about a letter he and Foreign Secretary Yvette Cooper wrote to the committee to say the security vetting was conducted ‘to the usual standard’. This, it said, concluded ‘with DV [developed vetting] clearance being granted by the FCDO’. It did not mention that the vetting had recommended he was not cleared.

His position is strengthened by his fellow former civil servants rushing to his defence.

UN humanitarian chief Tom Fletcher, a former No 10 adviser, added: ‘This is a guy who has public service and integrity stitched into his DNA in a way I haven’t seen in any other individual.

‘So he has had an utterly rough few days. He’s a strong character but I think he’s heartbroken.’

Former Conservative minister Graham Stuart quizzed Sir Keir over why senior civil servants Antonia Romeo and Cat Little were ‘still in post’. The pair came across the information that Lord Mandelson failed security vetting as part of the process to publish documents associated with his appointment as US Ambassador, but took weeks to inform the Prime Minister.

Mr Stuart said: ‘If Olly Robbins could and should have provided this information to the Prime Minister at the first opportunity, as he’s said today, surely the same applies to Cat Little and Antonio Romeo and the Cabinet Office officials who sat on this information for nearly a month?’

Sir Keir told MPs: ‘They acted entirely appropriately. They came across the information.

‘They took legal advice on who it could be disclosed to and disclosed it to me as soon as they got that legal advice.’