Keir Starmer's dramatic decision to sack the mandarin who approved Peter Mandelson's vetting backfired yesterday when Sir Olly Robbins told his side of the story for the first time.

In two-and-a-half hours of testimony to the foreign affairs committee, Sir Olly made it clear that No 10 was determined to get its controversial choice of US ambassador in place, whatever the risks.

He told of the pressure placed on the Foreign Office to get the vetting checks done quickly so Mandelson could be sent to Washington DC in time for Donald Trump's return to the White House.

And he told MPs on the committee that it would have been a huge problem if he had rejected the appointment.

Sir Olly also made another hugely damaging revelation: That No 10 had privately lobbied for Sir Keir's own spin doctor Matthew Doyle, later disgraced over his links to a paedophile, to be made an ambassador.

Sir Olly, a 51-year-old career civil servant, told of his sadness that he had lost his job as permanent under-secretary to the Foreign Office, and hinted that it may end up in court as he declined to reveal the exact details of his sacking by the PM.

The mandarin's claims included:

Pressure to get Mandelson over to Washington DC

Sir Olly took up his role in the Foreign Office on January 8, 2025, a month after Mandelson's appointment had been announced by Sir Keir.

He told MPs: 'I'm afraid I walked into a situation in which there was already a very, very strong expectation ... that he needed to be in post and in America as quickly as humanly possible.'

No 10 had told Sir Olly's predecessor they wanted it done 'at pace' before President Trump's inauguration on January 20.

By the time Sir Olly was in place, Mandelson's appointment had already been signed off by the King and the White House.

Throughout January, there was 'an atmosphere of constant chasing' with Downing Street asking 'has this been delivered yet', he told MPs.

He said there was a 'pretty unmistakable feeling' of not 'just please get this done quickly', but 'get it done'.

Sir Olly said he did not know if the PM's then chief of staff Morgan McSweeney, a protege of Lord Mandelson, had been behind the pressure.

He was asked if it was true that Mr McSweeney had phoned the previous Foreign Office chief Sir Philip Barton and told him: 'Just f***ing approve it.'

Sir Olly agreed the handover gave him the impression of an atmosphere of pressure but admitted: 'I don't remember Philip using those words.'

Downing Street's 'dismissive approach'

Even before he began speaking, Sir Olly had given the committee a dynamite letter showing just how invested No 10 was in Mandelson getting the country's most prestigious diplomatic posting.

He pointed out that the Government not only ignored the recommendation 'that security clearance be obtained before announcing a political appointee', but that the Cabinet Office even 'raised whether developed vetting (DV) was actually necessary' because Lord Mandelson was already a peer and a Privy Counsellor. Sir Olly later said the vetting process only went ahead because the Foreign Office 'put its foot down'.

He said the 'dismissive approach' was illustrated by the fact that the appointment had been announced long before vetting began – and Mandelson was already 'being granted access to highly classified briefing' before the checks ended.

Mandelson concerns were 'manageable'

Central to the scandal was the decision by Sir Olly to grant Mandelson developed vetting clearance despite concerns being raised by UK Security Vetting (UKSV) officials.

He disputed the claim by No 10, which contributed to his sacking, that the experts had refused to sign off on Mandelson and he had overruled them.

The mandarin said he had never even seen a form on which the UKSV can flag 'high concern' in a red box and recommend 'clearance denied'.

Instead, he said he had a meeting with the Foreign Office's head of security, Ian Collard, on January 29 at which he was given only an oral summary of the concerns raised – and was assured they were manageable.

'I was briefed that UKSV considered Mandelson a borderline case, and that they were leaning towards recommending that clearance be denied, but that the Foreign Office's security department assess the risks identified as of highest concern by UKSV could be managed and/or mitigated.'

Sir Olly divulged that the risks did not relate to Mandelson's friendship with the late paedophile Jeffrey Epstein, but he would not 'open that box' of what was discussed.

I wasn't allowed to reveal the issues

Despite telling how his department was under relentless pressure to rubber-stamp Mandelson's appointment, Sir Olly raised eyebrows by claiming he never told No 10 that he had approved developed vetting clearance the day after the security meeting.

'It was absolutely clear, not only that within minutes of us recording our decision to grant DV, Peter will have received a DV certificate, and it's entirely possible that Mandelson himself would have then told people it's been granted.

'I don't think I felt under any obligation to tell anybody.' Sir Olly was sacked after No 10 discovered he had failed to reveal the concerns raised at the time or over the subsequent year as the Epstein scandal blew up and Mandelson was sacked.

But he insisted he was not allowed to tell anyone what had gone on, saying: 'My understanding of custom, practice and guidance is that the decision-making within the box of the vetting process must remain entirely confidential.'

Told that the PM expected him to provide more information, Sir Olly replied: 'I hope it's clear from everything I said so far that I believe that's a misunderstanding and a dangerous misunderstanding of the necessity of confidentiality of the process.'

A diplomatic incident averted

Sir Olly agreed it would have 'damaged' Britain's relations with the US if the appointment of Mandelson had been scrapped at the last minute.

'The incoming administration [Trump] may well have commented on it publicly and it would, yes, have caused quite a quite an issue in the relationship.'

He insisted he was not influenced by the pressure but admitted: 'I was very conscious that if we went through the rigor of our process and decided against granting clearance, that that would have caused a real problem for the Government and a problem for the country.'

Why did PM announce appointment so early?

Sir Olly would not say he regretted granting Mandelson security clearance – but he did criticise the PM for announcing the appointment before the checks were done and despite all the risks being known about it.

He said: 'I regret that this process was not done before announcement. I regret that the due diligence process, which threw up as I understand it serious reputational risks, didn't colour the Prime Minister's judgment in making the appointment.

'There's quite a lot about this situation over the last year and a half I regret. I had no regrets about the work of my brilliant team and the judgment that we came to.'

A hint at possible legal action over sacking

Asked about what Sir Keir had said to him last Thursday when he sacked him, Sir Olly declined to provide details. He admitted: 'I regret that I, in my view, didn't have some of the points that the Prime Minister and others are making about the Foreign Office's decision making and about my accountability.

'I regret that those were not put to me before I received a letter dismissing me.'

Sir Olly said he did not 'fully understand the reasons that I'm in the position I am in' but is 'desperately sad' to have lost a job that he loved.

And he hinted at a possible legal challenge to his dismissal, saying he was in 'unknown territory' about his 'HR position'.