Image source, Reuters

The prime minister has repeatedly told MPs that "full due process" was followed in the appointment of Lord Mandelson as US ambassador.

Sir Keir Starmer has been accused by opponents of misleading parliament and will make his case to the Commons later.

Here are some of the key questions MPs will want him to answer:

• What did he know and when?
• Why did Starmer and his team not ask for more information?
• Did the PM mislead parliament?
• Why did Mandelson fail his vetting?
• Will he face further pressure after Monday's Commons appearance?

You can read more about this in our political reporter Jennifer McKiernan's story.

BBC Radio 4's Today programme has been speaking to Lord Simon McDonald, who is a former permanent under-secretary for the Foreign Office and head of the diplomatic service.

Asked if former top civil servant Olly Robbins was "thrown under the bus", McDonald says "yes".

McDonald says that the fact Robbins' removal from his position came on the same day the story first broke in the Guardian "shows to me that Number 10 wanted a scalp, they wanted it quickly".

"I cannot see that there was any process any fairness any giving him the chance to set out this case and that feels to me wrong," he adds.

Image source, US Department of Justice

Lord Mandelson, Starmer's pick for US ambassador, was sacked seven months into the job over his ties to the late convicted sex offender Jeffrey Epstein.

Mandelson has long argued that he accepted Epstein and his lawyer's version of events, and only discovered the truth after his death in 2019.

The BBC understands his position is he has not acted in any way criminally and that he was not motivated by financial gain.

Image source, AFP via Getty Images

Downing Street has said that the prime minister did not know about the outcome of Lord Mandelson's security vetting, while Starmer says he is "furious" about not being told.

But these denials haven't been enough to stymie the calls from opposition parties for Starmer's resignation.

• Conservative leader Kemi Badenoch has said the explanation from No 10 is "completely preposterous" and adds "all roads lead to resignation". She told a press conference on Friday that she is "considering every parliamentary option" to removing the prime minister and called on Labour MPs to "do the right thing" and get rid of him

Image source, PA Media

• Liberal Democrat leader Ed Davey has said the situation shows “catastrophically poor judgement” on a matter of national security, and that the evidence suggested Starmer had misled the public and Parliament
• Reform UK leader Nigel Farage has said there is “no doubt” the Commons was misled, and describes top Foreign Office official Olly Robbins as a “sacrificial lamb” after his effective sacking
• Plaid Cymru leader Rhun ap Iorwerth accuses the prime minister of becoming “distracted from his day job and failing those he serves”
• Green Party leader Zack Polanski has said on Friday there was "no way today should end" without Starmer's resignation, and branded any other outcome an “absurd scenario”
• The SNP's leader in Westminster Stephen Flynn says the prime minister is either “incompetent, gullible or a liar”, or he was “all three”

Labour's Secretary of State for Scotland Douglas Alexander says "absolutely" Keir Starmer can "survive the political scandal" from this Mandelson vetting row.

Claims that the prime minister is lying - including from Opposition Leader Kemi Badenoch - are "simply untrue", he tells BBC Breakfast.

"The reality is, Peter Mandelson should not have been appointed, the prime minister recognises and has stated repeatedly that that was a mistake," he says.

He adds that "lessons need to be learned" in relation to the appointment process, and Starmer will answer questions from MPs today about it.

Image source, PA

It emerged late on Thursday that the most senior civil servant in the Foreign Office, Olly Robbins, was leaving his post.

It came after the Guardian reported that his department didn't tell Prime Minister Starmer that Lord Mandelson had failed security vetting for the role of US ambassador, and decided to let him take up the role.

The BBC understands he was effectively sacked after Starmer and Foreign Secretary Yvette Cooper lost confidence in him.

Robbins was made permanent under-secretary at the Foreign Office in January 2025.

As department leader, this also made him the head of the UK's diplomatic service and the most senior policy adviser to the foreign secretary.

He was previously permanent secretary of the Department for Exiting the European Union in 2016, and former PM Theresa May's Europe adviser from 2017-19, overseeing Brexit negotiations.

He'd also served as principal private secretary for former PMs Tony Blair and then Gordon Brown.

Starmer is likely to argue this is all the fault of Olly Robbinspublished at 07:34 BST

07:34 BST

Henry Zeffman
Chief political correspondent

The prime minister’s argument today in its essence will be that all this is the fault of Olly Robbins, who was the head civil servant at the Foreign Office until he was sacked by Starmer in a phone call on Thursday night.

He will argue, first, that Robbins should not have overruled the vetting agency’s recommendation that Lord Mandelson not be given security clearance.

And second, he will argue that Robbins should have alerted him and the government about what had transpired far sooner, and certainly while he was facing intense questions about the decision to appoint Mandelson.

Robbins will have his chance to answer all that when he is expected to appear before a committee of MPs tomorrow.

Expect opposition parties to question whether the prime minister could and should have done more to find out the full sequence of events before facing questions on this. Was he culpably incurious?

But it is worth stressing that as of this morning it does not feel like Labour MPs are seriously angry about this. That alleviates the pressure on Starmer in the short term.

But they are seriously frustrated that the Mandelson saga has entered a fresh chapter, and that frustration could increase the danger to Starmer’s position in the medium term.

Image source, PA Media

Keir Starmer would have blocked the appointment of Lord Mandelson as US ambassador had he known he failed security vetting, ministers have said.

Technology Secretary Liz Kendall said on the BBC's Sunday with Laura Kuenssberg that Starmer was told Mandelson had been granted developed vetting status, adding: "If he had known that UK security vetting hadn't cleared him, he would not have made that appointment."

Kendall's defence of the prime minister echoed remarks by Deputy PM David Lammy, who has told the Guardian, external he had "absolutely no doubt at all" that the prime minister "would never, ever have appointed" Mandelson if he had known he failed vetting.

Lammy, who was foreign secretary at the time of Mandelson's appointment, says neither he nor his advisers had been told about the vetting process.

• You can read more about what ministers have been saying in this story

Speaking to reporters on Friday, Prime Minister Keir Starmer said he would go to Parliament to "set out all the relevant facts in true transparency so Parliament has the full picture" about Lord Mandelson's appointment as ambassador to the US.

We're expecting that address to the House of Commons at 15:30 BST.

Starmer vehemently denied knowing that Mandelson had failed his security vetting, calling it "staggering".

"That I wasn't told that he'd failed security vetting when I was telling Parliament that due process had been followed is unforgivable," he said.

"Not only was I not told, no minister was told and I'm absolutely furious about it."

He added that: "It is totally unacceptable that the prime minister making an appointment is not told that security vetting has been failed."

Image source, Reuters

This is one of the questions MPs will be hoping to hear answered.

The remaining documents relating to Lord Mandelson's vetting and appointment are set to be released imminently. They were initially withheld on the orders of the Metropolitan Police, which is investigating Lord Mandelson for potential criminal activity.

Lord Mandelson has not responded to requests for comment but the BBC understands his position is that he has not acted in any way criminally and that he was not motivated by financial gain.

The documents also need to be inspected by the Intelligence and Security Committee of cross-party MPs, which is trying to balance allowing as much information as possible into the public domain without compromising national security.

Image source, Reuters

In November, the then head of the civil service, Sir Chris Wormald, said Lord Mandelson was not formally interviewed for the role of US ambassador.

Wormald said Mandelson was not directly asked in person about any conflict of interest, but instead needed to fill in a form aimed more at potential financial conflicts. This process has now been changed.

Details of the due diligence checks made before Lord Mandelson's appointment, carried out by the Cabinet Office on behalf of Downing Street, are still to emerge.

However, Wormald told MPs in November that the document did contain an "initial assessment" of mitigations around potential professional or financial relationships and noted the inclusion of "a general reputational risk" linked to Epstein.

Sir Keir Starmer is once again coming under pressure over the appointment of Lord Mandelson as the UK's ambassador to the US.

The Labour grandee was given the post in December 2024 only to be sacked a year later over his ties to the late convicted sex offender Jeffrey Epstein.

Questions have been raised over what the prime minister knew when about his appointment.

Image source, Reuters

The prime minister is facing calls to resign as he heads to the House of Commons later to address Lord Mandelson's appointment as UK ambassador to the US.

It emerged last week that Lord Mandelson had failed a vetting process to undertake the role and yet was still sent to the US on the diplomatic mission.

Starmer has denied knowing that the peer had failed the process, saying it was "staggering" that he hadn't been told.

The BBC's political editor Chris Mason reported that Lord Mandelson himself was also unaware he had failed it.

Top civil servant at the Foreign Office Sir Olly Robbins has resigned following the scandal and now opposition voices are calling for the prime minister to do the same.

But some Labour ministers have defended the PM, saying he would not have made the appointment had he known.

We'll bring you all the latest updates and analysis right here on this page.