Monday briefing: How is it possible the prime minister didn’t know about Mandelson’s vetting failure?

Monday briefing: How is it possible the prime minister didn’t know about Mandelson’s vetting failure?

On Friday, Starmer said he was “absolutely furious” and described the situation as “totally unacceptable”. But the episode has once again raised questions about his political judgment, with opposition parties – and some of his own MPs – calling for his resignation.

The story has ramifications beyond the immediate fallout for Starmer. For today’s newsletter I spoke to the Guardian’s head of investigations, Paul Lewis, about what the story tell us about how power operates inside government – and who is really in charge. First, the headlines.

Iran | Tehran is not planning to take part in new talks with the US in Islamabad, Iranian state media reported, as its military accused America of violating a fragile ceasefire by attacking a cargo ship.

US news | At least eight children were killed and two adults wounded in a mass shooting in Shreveport, Louisiana. Police said the suspect, who died after a police pursuit, killed seven of his own children and wounded their mother, as well as killing another child.

UK politics | Keir Starmer will deliver a high-stakes statement to MPs on Monday setting out how Peter Mandelson was able to take up his role as UK ambassador without the Foreign Office revealing it had overruled the decision to fail his vetting.

Protest | Seven people from an activist group calling for higher taxes on the super-rich have been arrested by police on suspicion of conspiracy to steal after a plot to steal from high-end stores was uncovered.

Crime | A woman has been arrested on suspicion of attempted murder after a car hit pedestrians in central London in the early hours of yesterday morning. A woman in her 30s was in hospital in a critical condition and a man in his 50s suffered life-changing injuries.

Peter Mandelson was appointed the UK’s ambassador to Washington in February 2025. He was sacked in September 2025 after documents released in the US revealed the extent of his ties with convicted sex offender Jeffrey Epstein, which the Foreign Office said were “materially different from that known at the time of his appointment”.

But “who knew what, and when” about his relationship with Epstein has never been satisfactorily explained despite the release of documents to parliament about the appointment process. Then it appeared there might be another dimension – that Mandelson had failed security vetting but had been given the role anyway.

“The moment we got a sense this story might be true,” Paul tells me, “my colleagues Henry Dyer, Pippa Crerar and I worked relentlessly to stand it up.”

If, after his appointment as US ambassador, Peter Mandelson failed his UK security vetting – and then that decision was overruled by officials at the Foreign Office – unbeknownst, allegedly, to the prime minister or other members of the cabinet, Paul knew it needed to be in the public domain. Once it was, he predicted there would be very significant ramifications: for Keir Starmer, for Olly Robbins, and for the wider intelligence and security establishment – all of which is just starting to pan out.

After Labour’s July 2024 election victory, Mandelson quickly re-emerged as an influential figure around the new government, advising ministers and building ties in No 10 before being announced as the next US ambassador. It now appears that in January 2025 he failed developed vetting clearance – a rare outcome – only for the decision to be internally overruled by the Foreign Office, allowing him to take up the post.

On 2 September last year, the closeness of Mandelson’s relationship to Epstein was laid bare in the first tranche of files released in the US. On 10 September Starmer said in parliament he had “confidence in him”, and on 11 September a Downing Street spokesperson told the media that Foreign Office vetting had been done “normal way”. Later that day Starmer fired Mandelson.

In February, Starmer said that Mandelson had passed vetting, with Morgan McSweeney then resigning as Starmer’s chief of staff, saying he took full responsibility for advising Starmer to appoint Mandelson.

In March, document released to parliament stated that national security adviser, Jonathan Powell, had doubts about Mandelson’s appointment, describing it as “weirdly rushed”, but crucially the documents do not disclose that Mandelson failed security vetting.

Why does it matter beyond Starmer?

“If you believe Downing Street, no politician was told – not David Lammy as foreign secretary, and not the prime minister. That’s extraordinary.”

Paul is not alone in thinking this is extraordinary. Others have gone further. Veteran Labour MP Jon Trickett said: “It simply doesn’t sound credible,” and Conservative leader Kemi Badenoch described the idea as “completely preposterous” and said there was “deliberate dishonesty”.

Paul tells me that as much as this is clearly a very significant political story, what really fascinates him is “the wider question of where power resides in the British state”.

“It’s a massive Westminster story,” he says. “About Starmer’s candour in parliament and in public, his judgment in appointing Mandelson, and the resignation of the Foreign Office permanent secretary, Olly Robbins.

“But what this episode seems to reveal is the really significant, and potentially unchecked, power of senior civil servants and officials.”

According to multiple sources, Mandelson was initially denied clearance in late January 2025, but Starmer had by then announced he would be making Mandelson the UK’s chief diplomat in Washington, potentially posing a dilemma for officials at the Foreign Office.

Paul points out it very much reminds him of the television sitcom Yes, Minister with its wily senior Whitehall mandarins manoeuvring politicians, running the show behind the scenes by seemingly pressing ahead with a plan without consulting ministers about an important change of circumstances. As revealed on Friday, Starmer was apparently left in the dark about sensitive information relating to Mandelson’s security vetting by two other top civil servants besides Robbins, including the recently appointed cabinet secretary, Antonia Romeo – who has known since March.

Who is really making the decisions?

Mandelson’s role would have been one of the most sensitive in government.

“Think about the implications,” Paul says. “The UK’s most senior diplomat in Washington, dealing with intelligence from GCHQ and the NSA, handling top-secret material, was allowed into that role despite failing a vetting process that even relatively junior civil servants have to pass.