Starmer cried: ‘You’re supposed to be protecting me’. The showdown between PM and key aide that’s the talk of Westminster

According to the Whitehall grapevine, it was the moment that growing tensions between the two most senior men in the British Government finally exploded into the open.

‘You are supposed to protect me from things like this!’ a furious Sir Keir Starmer is said to have bellowed at Morgan McSweeney, the man dubbed The Real Deputy Prime Minister.

‘That’s exactly what I was trying to do!’ Mr McSweeney roared back.

The extraordinary exchange – relayed to The Mail on Sunday by a highly placed source – came after Sir Keir returned to No10 on Wednesday following his Commons mauling over Peter Mandelson’s links to paedophile Jeffrey Epstein.

No 10 denies the encounter took place as described – and even tried to deny that chief of staff Mr McSweeney was in the country at the time, before backtracking.

But what is not in question is that the Mandelson scandal has turned into a full-blown political crisis which could lead to the end of Starmer’s premiership.

Despairing Labour MPs are looking to Manchester Mayor Andy Burnham for salvation, with Lucy Powell running as his ‘proxy’ in the deputy leadership election.

Supporters hope Mr Burnham will return to the Commons in a by-election, making him eligible for a leadership bid.

Even the previously loyal Guardian newspaper has turned on Sir Keir, writing yesterday that ‘an operation to dethrone Starmer is now under way’.

In lines which will have sent a chill down the Prime Minister’s spine, the Left-wing paper wrote: ‘The question being asked in the tea rooms and bars and corridors of Westminster is whether Starmer is up to the task of finding the solutions the country needs. 

‘And, increasingly, the conclusion reached among MPs is: “No”… the doubt has set in. Not just that Starmer has shown a lack of political judgment, ideological vision, or – especially when compared with the charisma of Nigel Farage – personality. But that he never had it in the first place.’

The newspaper said Cabinet ministers were part of ‘below-the-radar operations to oust the Prime Minister’, with some doubting he will even survive until May’s local elections.

The seeds of this disaster were sown in November when Donald Trump won the US presidential election.

Until then there had not been a consensus in No 10 over who should succeed Karen Pierce as our Ambassador in Washington – but Trump’s victory ended the argument. 

One minister says: ‘Morgan was adamant at that moment it had to be Peter. He said our priority had to be securing a trade deal with the US, and that as a former EU trade commissioner, Mandelson was the man to do it.’

Lord Mandelson and Mr McSweeney have long been close.

The peer once said: ‘I don’t know who and how and when [McSweeney] was invented. But whoever was responsible… they will find their place in heaven’.

Mr McSweeney assured Sir Keir he could manage any potential ‘issues’ with Lord Mandelson’s appointment.

Crucially, he also insisted on taking direct control of the recruitment process. 

According to senior diplomatic sources, the Foreign Office was ‘largely cut out of it all’ as Mr McSweeney pushed for the appointment.

This also extended to Lord Mandelson’s security vetting. According to a senior source: ‘Because Mandelson wasn’t a career civil servant, he did not go through the traditional vetting processes. 

‘Normally an ambassador will have had been subject to a detailed security assessment at the time of their appointment, and additional regular vetting every four or five years. But this didn’t apply in this case.’

Instead, sources say the security services produced a single report on any potential issues raised by Lord Mandelson’s appointment. After sharing information with their opposite numbers in the US State Department, a number of ‘red flags’ were raised.

‘Officers had a number of concerns,’ a security source revealed. ‘Epstein was one, but there were also issues relating to some of Mandelson’s business links with Russia and China.’

The incoming Trump administration had wanted Ms Pierce to stay in post for at least another year – and are now lobbying No 10 for her to be sent back across the Atlantic for a second stint.

The US officials argued that if Ms Pierce was not going to have her tenure extended then the job should go to MI6 boss Sir Richard Moore who, a source said pointedly, ‘could actually be trusted with sensitive material’.

However, in an echo of the so-called Dodgy Dossier which paved the way to war in Iraq, sources claim that the objections were watered down.

‘The concerns about Mandelson were quite strong in the original version,’ a senior government official revealed. ‘But then the report was rewritten. It was deemed politically inconvenient to present the original to the Prime Minister.’

No 10 denies that the advice was ‘sexed down’.

Soon after Lord Mandelson’s appointment, Mr McSweeney began leaning more heavily on him for broader advice on how to manage international and domestic policy.

Inside the Foreign Office people began to call him ‘The Real Foreign Secretary’. One official said at the time: ‘Morgan is relying on Peter more and more. They’re on the phone to each other on a weekly basis. And their conversations are much wider than how to manage Trump.’

That is presumed to be the reason why Mr McSweeney was so keen to hang on to Lord Mandelson, even his when his adoring, ten-page note in Epstein’s ‘birthday book’ was released by US congressional panel.

It is also thought to be why Mr McSweeney allowed the Prime Minister to say he had ‘full confidence’ in the ambassador in the Commons on Wednesday, a day after the Foreign Office had alerted them to the imminent release of explosive emails.

The Foreign Office was soon in full ‘I told you so mode’ with Mr McSweeney. Sir Olly Robbins, the most senior civil servant in the department, assembled an ad hoc group of Whitehall experts in ethics, who drew up a list of questions to ask Lord Mandelson, including details of his last contact with Epstein. When no answer was forthcoming, Sir Olly communicated this to No 10.

This is the point when Mr McSweeney finally accepted that Lord Mandelson’s position was untenable and said this to the PM – which is understood to have triggered the exchange we report

Mr McSweeney then fled No 10 to attend meetings in Brussels.

Lord Mandelson left an immediate legacy in the form of the newly reshuffled Cabinet. On the morning Angela Rayner resigned over failing to pay the full stamp duty bill for her seaside flat, Lord Mandelson was spotted entering No 10.

The official line was that it was just a scheduled meeting. But in truth he had arrived to help Mr McSweeney to plan the reshuffle.

According to one minister, it was Lord Mandelson who advised Mr McSweeney to move respected Business Secretary Jonathan Reynolds to chief whip, and replace him with Science Secretary Peter Kyle, a move that bemused much of Westminster.

The minister said: ‘Kyle is one of Peter’s friends and Mandelson was obsessed with locking down the trade deal with Trump, so he wanted one of his allies in post.’

Sir Keir acquiesced to the move. But by now he was privately starting to lose patience with Mr McSweeney.

According to allies, he had been angered by the publication of a book about Labour’s inner workings called Get In.

Mr McSweeney’s friends had briefed the authors that he was the true architect of the election victory, and that Sir Keir was merely the figurehead of the campaign.

Sir Keir also felt Mr McSweeney had ‘bounced’ him into delivering a speech claiming Britain was becoming ‘an island of strangers’.

He later publicly disowned it. As he agreed to the latest Mandelson/McSweeney initiative, the Prime Minister had little idea a new set of problems were only just beginning.

A No 10 source said the exchange between Sir Keir and Mr McSweeney had been ‘fabricated’ and that Mr McSweeney had not been in the country, before conceding that he had been in No 10 until he caught the 5pm Eurostar to Brussels.

The source added: ‘They had one conversation about this and it was nothing like that. They don’t talk to each other in that way.’