Morgan McSweeney's lengthy questioning by MPs over the Mandelson vetting scandal seemed to cause one man to nod off on Tuesday, on what is sure to be a make-or-break day for the Prime Minister.

Sir Keir Starmer's former chief of staff was giving evidence to the Foreign Affairs Committee in relation to the appointment of Peter Mandelson as US ambassador.

Mandelson was sacked from the role in September 2025 over his friendship with convicted paedophile Jeffrey Epstein, which continued after the financier had been convicted of sex offences involving minors.

His appointment sparked fresh outrage among MPs last week in recent weeks after it emerged he failed vetting procedures, with chief Foreign Office civil servant Sir Olly Robbins overruling the recommendation.

In today's hearing, the man, seated behind Mr McSweeney in a pink shirt and striped tie, appeared to close his eyes at points during proceedings. 

He wasn't the only observer spotted struggling to keep his attention on proceedings, with veteran MP Diane Abbott also seen shutting her eyes as she listened to Mr McSweeney's answers. 

It comes as the former chief of staff apologised for his role in the scandal, saying Sir Keir 'relied on my advice and I got it wrong'.

Mr McSweeney said he believed Mandelson was the best choice because Britain was 'exposed' on trade after Brexit and with Donald Trump in the White House.

He acknowledged that the New Labour architect had been a 'confidante' - but denied he was a 'mentor'.

'What I did do was make a recommendation based on my judgment that (Mandelson's) experience, relationships and political skills could serve the national interest in Washington at an important moment. That judgment was a mistake,' Mr McSweeney said.

'I would never have considered that acceptable. These processes are in place to protect our national security.'

And in an extraordinary admission, Mr McSweeney admitted he did not think Mandelson had been entirely honest when he asked him follow-up questions about his relationship with Epstein.

'My thinking at the time was I put follow-up questions to him in writing, and that if a senior member of staff did that, he would feel more obligated to give the truth and the full truth. 

'I didn't feel that I got that back from him. But it wasn't my decision, it was the Prime Minister's decision.' 

He added that at the time he had believed Mandelson, but that the reality of his 'advisor's' relationship with Epstein was 'way, way, way worse' than he had suspected.

'The nature of the relationship that I understood he had with Epstein was not a close friendship. How I understood it at the time was a passing acquaintance that he regretted having and that he apologised for.

'What has emerged since then was way, way, way worse than I had expected at the time, and it was when I saw the pictures, when I saw the Bloomberg questions in September 2025, I have to say it was like a knife through my soul.'

His evidence is being given just hours before a crunch vote in the Commons for Sir Keir over whether he misled MPs. 

Conservative Leader Kemi Badenoch has led the charge to call a vote on whether to refer the PM's actions to the cross-party privileges committee, after the Prime Minister told MPs that 'full due process' was followed in the appointment.

He has also denied claims that pressure was put on the Foreign Office over Mandelson's vetting process. 

Writing in the Daily Mail today, Kemi Badenoch said MPs of all stripes have a duty to hold Sir Keir to account for treating Parliament with 'contempt'.

She told Labour backbenchers they are 'not in the Commons simply to protect the PM from embarrassment'.

'Labour MPs now face a test of their own,' the Tory leader said.

'They can circle the wagons, obey the Whips and tell themselves this is just politics. Or they can remember they are MPs before they are members of the Labour Party.'

Labour MPs are expected to be whipped to vote against the opposition motion, with allies of the PM said to be confident they can keep calls for him to go at bay, with local elections just two weeks away.

Earlier, the Foreign Affairs Committee heard from former chief civil servant to the department Sir Philip Barton.

Sir Philip said he only learned the Government wanted to appoint Lord Mandelson to the post on December 15, 2024.

Sir Keir had been 'made aware of the risks, and had accepted those risks and decided to proceed', Sir Philip added.

He denied claims which emerged last week that Mr McSweeney had told him to 'just f***ing approve' the appointment in a phone call.

But he added there was 'pressure' from No10, telling the committee: 'There's two possible questions here. Question one is, was there pressure on the substance of the DV [developed vetting] case?' he said.

'Question two is, was there pressure to get the DV case done in a particular timeframe?'

He continued: 'Answer one is, during my tenure, I was not aware of any pressure on the substance of the Mandelson DV case.

'Question two, was there pressure? Absolutely.'

He added: 'I don't think anyone could have been in any doubt in the department working on this that there was pressure to get everything done as quickly as possible.'

It also emerged during today's hearings that there was no contingency plan in place for what happened if Mandelson failed vetting. 

'It would have been a crisis if we got to the point where he had no vetting clearance, that would have been a crisis,' he said.

Sir Phillip indicated the 'crisis' would have been caused by the fact Mandelson had already been announced as the next US ambassador before vetting had taken place, something he said was highly unusual.

He also had concerns about the appointment, but told the committee he had no opportunity to discuss them because there 'was no dialogue' with No10. 

'I had a concern that a man who demonstrably from the public record at the time – and it was clearly much bigger than we all knew – had a link to Epstein, and that Epstein through both the presidential election campaign in the US and more generally in US politics, had been and was a controversial figure, and I was worried that this could become a problem in future…

'That is a very candid account of probably what I was thinking at the time, but there was no space or avenue or mechanism for me to put that on the table.

'A decision had been taken. It was a political decision.'

The hearings came on the same day as a debate on the Conservatives' motion to force a referral the PM's actions to the cross-party privileges committee to investigate whether the Commons has been misled.

A three-line whip is in place for the vote for Labour MPs, in contrast to when Sir Keir called a similar vote against Boris Johnson over Partygate. For that vote, the then-opposition leader said MPs should be free to vote according to conscience.

The vote is set to take place this evening, and will be billed as a landmark moment in the event of a defeat for the Government.