Cabinet rumblings are growing today as Keir Starmer engages in an extraordinary deathmatch with Whitehall over the Mandelson scandal.

Ministers have voiced concerns after explosive testimony from the Foreign Office chief who was sacked for not telling the PM that Mandelson failed security vetting.

Sir Olly Robbins told MPs Downing Street 'chased' to finalise the posting as US ambassador and was 'dismissive' of the need for any checks.

The Foreign Affairs Committee also heard claims that Sir Keir's former chief of staff called Sir Olly's predecessor insisting: 'Just f***ing approve it.' 

Opening another damaging flank, Sir Olly revealed that No10 tried to get Sir Keir's spin doctor Matthew Doyle a plum posting as a 'head of mission' abroad. 

Lord Doyle later left Government, and has since been stripped of the Labour whip over campaigning for a councillor who had been charged with child sex offences. He denied seeking a diplomatic post today.

The Mandelson debacle dominated the Cabinet's weekly meeting this morning. Sir Keir told his team that Sir Olly had to go because he made an 'error in judgment' – the same thing the premier has admitted making himself over the appointment of Mandelson. 

In the Commons, Foreign Secretary Yvette Cooper said she was 'concerned' about the claim No10 kept efforts to make Lord Doyle an ambassador from her predecessor David Lammy. She said she was clear the appointment would have been 'inappropriate'. 

Earlier, Ed Miliband heaped woe on the premier by revealing he had warned against making Mandelson US ambassador.

The Net Zero Secretary said he told Mr Lammy he thought the appointment could 'blow up' – and the then-Foreign Secretary shared his concerns. 

Yesterday Scottish Secretary Douglas Alexander raised eyebrows by saying it was 'not certain' the PM would lead Labour into the next election. 

The furore has renewed doubts about whether Sir Keir can cling on in No10, after he was almost ousted in a coup in February. It is barely a fortnight until local elections where Labour is facing a battering at the hands of Reform.

Kemi Badenoch said the evidence from Sir Olly was 'devastating' and Sir Keir should quit.

Meanwhile, as ministers scramble to get a grip on the spiralling crisis, the PM's top ally Darren Jones this afternoon announced a 'leak inquiry' into how information about Lord Mandelson's security vetting was given to a newspaper.

Sir Olly's appearance came after he was squarely blamed by Sir Keir for failing to tell him officials had advised against giving Mandelson the key job.

During a marathon Commons session last night – which saw the Labour benches alarmingly empty behind him – Sir Keir said he had been 'deliberately' kept in the dark. 

But Sir Olly – who took on his role after Mandelson was publicly announced, but before he was formally confirmed as US envoy – said there was an 'atmosphere of pressure'. 

'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 soon as possible,' he said.

Giving evidence this morning, Sir Olly said he had received a letter terminating his employment yesterday but still did not 'fully understand' why he was sacked. He is now thought to be consulting lawyers, which might result in a huge payoff. 

The ousted civil servant said he had been verbally briefed on the vetting process by the Foreign Office's security chief in January last year, and had been told the team were 'leaning' towards rejecting Mandelson.

However, he argued officials agreed there were ways of managing the risks and he had been empowered to go ahead.

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

'I was also told that the risks did not relate to Mandelson's relationship with Jeffrey Epstein.

'And I was told that UKSV acknowledged, I don't know in what way, but acknowledged that the Foreign Office might wish to grant clearance with appropriate risk management.'

By the time Sir Olly became head of the Foreign Office, he said the Cabinet Office had carried out due diligence, and the King had already approved the posting.

He said the US had also given 'agreement' and dropping Mandelson at that stage would have 'caused quite an issue'.

'If the nomination had changed after that point, the incoming administration may well have commented on it publicly and it would have caused quite an issue,' he said. 

In a letter to the committee, Sir Olly said: 'Due diligence (which assesses reputational suitability and checks if a candidate is fit to serve) had been completed by the Cabinet Office.

'Mandelson was being granted access to highly classified briefing on a case-by-case basis.'

He said this 'resulted in a dismissive approach' to whether Developed Vetting (DV) – the most intensive process of clearance – was needed. 

'Nonetheless, despite this atmosphere of pressure, the department completed DV to the normal high standard,' he added.

Sir Olly pointed out that Sir Keir had not followed the advice of the Cabinet Secretary, who recommended in November 2024 that security clearance be obtained before any political appointee was selected to Washington.  

He added: 'After the announcement, I believe the Cabinet Office raised whether DV was actually necessary. 

'I understand the Foreign Office insisted that DV was a requirement before Mandelson took up his post in Washington.' 

At the hearing, Sir Olly was pressed whether Sir Keir's former chief of staff Morgan McSweeney had been the one pushing the appointment, but refused to name individuals.

Sir Olly was asked about an alleged call from Mr McSweeney to Sir Philip Barton, who was permanent under-secretary at the Foreign Office previously.

Committee chair Emily Thornberry said Mr McSweeney was reported to have told the mandarin: 'Just f***ing approve it'. 

Sir Olly said: 'Certainly Philip's handover to me has contributed to my strong sense that there was an atmosphere of pressure and a certain sense of dismissiveness about this DV process.'

He added that he did not 'remember' Sir Philip 'using those words' about the call, but he was 'not the sort of person' who would have 'reported them verbatim'.

Sir Olly also disclosed that 'several discussions were initiated by No10 with me about potentially finding a head of mission opportunity for Matthew Doyle, who was then the PM's head of communications'.

'I was under strict instructions not to discuss that with the then Foreign Secretary, which was uncomfortable,' he told the MPs.

Sir Olly highlighted that he had been looking at 'serious reform' and job losses at the Foreign Office at the time.

'I found it very hard to think how I would explain to the office what the credentials of Matthew were to be in an important head of mission role when I was in danger of making very experienced senior diplomats leave the office,' he said.

'I did my duty, I looked at the forward look of available jobs, I shared with No10 what some of those might be. It was, to be honest, hard to find something that might be suitable.

'But I also felt quite uncomfortable about it. I kept giving advice that this would be very hard for the office and was hard for me personally to defend.'

In February this year Lord Doyle apologised for his past association with Sean Morton, a former Labour councillor in Moray who admitted indecent child image offences in 2017.

Lord Doyle – who has been suspended from the party – campaigned for Morton after he was charged with possessing and distributing indecent images of children in December 2016.

'At the point of my campaigning support, Morton repeatedly asserted to all those who knew him his innocence, including initially in court,' the peer said.

'To have not ceased support ahead of a judicial conclusion was a clear error of judgment for which I apologise unreservedly.'

Sir Olly said Mandelson was also asked about the prospect of a role in Washington for Lord Doyle.

'I think subsequently, or maybe simultaneously, Mandelson was asked about whether there was a job that could be made available in the US network,' he told MPs.

'And so I think the fact that No10 was interested in potential diplomatic options for Doyle was probably a bit more broadly known than I realised at the time.'

Sir Keir was asked in the Commons yesterday whether he knew of any other cases apart from Mandelson where political appointments had been attempted to diplomatic posts, and dodged answering directly – saying he would have to check.

Downing Street did not deny that the PM tried to get Lord Doyle installed in a diplomatic post. 

Ms Cooper was challenged on the claim in the House afterwards, and said: 'I am of course extremely concerned at any suggestion that the permanent secretary or permanent under-secretary of the Foreign Office would be told not to inform the Foreign Secretary.

'I can also confirm the case that he raised, it would not have been an appropriate appointment as well.'

Lord Doyle said this afternoon: 'I have never sought any head of mission, ambassador or any equivalent leadership-type posting.

'I was never aware of anyone speaking to the FCDO about such a role for me.

'My desire after leaving No10 was to stay in UK politics.'

In another swipe at the PM, Sir Olly said he regretted that some of the allegations about his conduct were not put to him before he was sacked.

'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,' he said.

Sir Olly said he was personally upset at losing his role which he 'loved'. 

The official readout of the weekly Cabinet meeting suggests that despite the ongoing Iran war, the Mandelson row was the only issue discussed. There was a 'political discussion' afterwards. 

'The Prime Minister concluded by saying that Sir Olly Robbins made an error of judgment, but that he is a man of integrity and professionalism,' the readout said. 

In an emergency debate on the row in the Commons, Mrs Badenoch said the idea that Downing Street is the victim of others not following due process is 'laughable'.

'The Prime Minister… placed top secret intelligence in the hands of a man he knew to be a national security risk,' she said.

'He did so before the official security vetting, not just knowingly, but deliberately, and to an extent that left a senior civil servant, with a distinguished career, under the clear and obvious impression that the vetting must return only one possible outcome: that Peter Mandelson was appointed.

'None of this was following full due process, by the letter or the spirit of that phrase. This is no longer just about what the Prime Minister was or wasn't told. This is about what he did before the vetting process had even started.

'And we now know that Mandelson wasn't a one-off, according to Sir Olly Robbins, Number 10 also asked for the disgraced Matthew Doyle, the Prime Minister's then director of communications, to be made an ambassador. Astonishingly, the Prime Minister's office even told Robbins to keep this request a secret from the Foreign Secretary.

'The idea that it is Number 10 who are the victims of others not following due process is, quite frankly, laughable.'

Mandelson spent nine months as US ambassador before fresh details of his relationship with paedophile Jeffrey Epstein emerged.

He was a political appointment to the plum diplomatic role, rather than the Washington job going to a career diplomat.

Touring broadcast studios for the Government this morning, Mr Miliband said Sir Keir had acknowledged Mandelson should never have been appointed.

He told Sky News: 'I steered well clear of Peter Mandelson when I became Labour leader in 2010.'

Asked what he thought when Lord Mandelson's appointment was announced, he said: 'That it could blow up, that it could go wrong.'

He added: 'I had a conversation with David Lammy about it before the appointment and I said I was worried about it… I think he was worried about it too.'

Pressed if Sir Keir should lose his job, he said: 'I don't think so, no. Obviously I don't.

'I think prime ministers make errors. Prime ministers are fallible. Prime ministers are human.'

Mr Miliband insists he has no ambitions to take over from Sir Keir – but many at Westminster regard him as on manoeuvres.

Another potential rival, Angela Rayner, is set to make a pointed intervention urging Labour to be 'bolder' at a conference this evening. 

Donald Trump waded into the row overnight, jibing that Mandelson was a 'really bad pick' for the job of US ambassador.

Escalating his spat with the PM over the Iran war and trade, the US President wrote on Truth Social: 'Prime Minister Keir Starmer of the United Kingdom acknowledged that he "exercised wrong judgement" when he chose his Ambassador to Washington.

'I agree, he was a really bad pick.'

Mr Trump added: 'Plenty of time to recover, however! President DJT.'

One of Sir Keir's reasons for picking Mandelson was his hope that the smooth-talking Labour veteran would charm Trump.

That seemed to pay off when, during a trade deal announcement in last May, the President purred over Mandelson's 'beautiful accent'.

Sir Keir endured a torrid grilling in the Commons yesterday, with Speaker Lindsay Hoyle allowing the session to run for nearly two and a half hours following his own clash with the PM the previous week.

The premier was drowned out by mocking laughter as he acknowledged that his own version of events 'beggars belief'.

He struggled to explain why he appointed Mandelson before he had been vetted, despite being warned about his friendship with Epstein and business links to China and Russia.

Sir Keir denied misleading MPs over his decision to appoint the disgraced Labour peer as ambassador to the United States.

He admitted it had been a mistake to bring back Mandelson, describing it as 'wrong' – and insisted he would 'take responsibility' for that.

But he claimed he would never have given the Labour grandee the job if he had known that he failed security vetting.

Instead he angrily blamed the Foreign Office and Sir Olly.