The latest two witnesses to testify to parliament over Peter Mandelson’s appointment had plenty to offer headline writers. “A toxic hot potato” was how Philip Barton, the former top civil servant in the Foreign Office, described Mandelson’s links with Jeffrey Epstein, a view he would have shared with Downing Street if only he’d been asked.

“A knife through my soul” was how Morgan McSweeney, the prime minister’s former chief adviser, described the moment he found out the true nature of Mandelson’s relationship with the convicted sex offender.

But the most interesting parts of both men’s evidence on Tuesday were those that addressed the question at the core of the scandal: was the Foreign Office’s decision to grant Mandelson security clearance against the advice of the vetting agency influenced by pressure from Downing Street?

Both Barton and McSweeney agreed there was pressure put on the department over Mandelson’s security vetting. Both, however, maintained it had no bearing on the decision in late January 2025 to grant Mandelson clearance.

This idea, that there was pressure, but it had no impact, has emerged as the single point of consensus unifying the warring branches of government. The problem, for sceptics at least, is that it strains credulity.

First up was Barton, who was the top civil servant at the Foreign Office when Mandelson’s appointment was announced. Within weeks, Barton had departed to make way for Olly Robbins, who was permanent secretary when the vetting process was completed.

Barton told the foreign affairs select committee that when he was told, in mid-December 2024, that Downing Street wanted to send Mandelson to Washington, the decision was a fait accompli. “At no point did anyone ask or consult me,” he said. “I was presented with a decision and told to get on with it.”

As a former deputy US ambassador who was at the time running the UK’s diplomatic service, Barton might have been expected to have a say over the pick for the person who would run the Washington embassy. He made clear that, had he been asked, he might have had to relay his concern that Mandelson’s relationship with Epstein, which was public knowledge, could become a “problem in future”.

However the key issue for Barton related to the question of pressure: who was applying it, against whom, and to what end? When he gave evidence last week, Robbins talked of “constant pressure” from Downing Street. He described an atmosphere of “not just ‘Please get this done quickly’” but also, he pointedly made clear, “’Get it done’”.

Yet Robbins insisted the pressure to get it done had no bearing on his decision to grant Mandelson clearance, against the advice of UK Security Vetting (UKSV), in order for him to take up his post in Washington weeks later.

Keir Starmer, in the House of Commons last week, rejected the idea pressure had been applied, insisting: “No pressure existed whatsoever in relation to this case.” Sensing, perhaps, that he might have overdone it with the word “whatsoever”, he told the Sunday Times that there were “different types of pressure” and he’d only been referring to one type when he briefed MPs.

The prime minister said there was the “Can we get get this done quickly” variety of pressure, which was not unusual. That, Starmer said, was very different to the idea anyone should “disregard the security vetting element and give clearance” to Mandelson.

That view was echoed by on Monday night by Ian Collard, the Foreign Office security official who briefed Robbins on UKSV’s findings and appears to have had a role in finding a way to give Mandelson clearance with mitigations put in place.

Collard told the committee via a letter that he “felt pressure to deliver a rapid outcome to the vetting clearance”. But that pressure, he stressed, did not influence his “professional judgment”.

On Tuesday, Barton became the third top official to speak from the same script. There was, he said, “absolutely” pressure from Downing Street to get bureaucratic processes completed urgently so that Mandelson could be in post by the time of Donald Trump’s presidential inauguration on 20 January.

But Barton said he was “not aware” of any pressure over the substance of Mandelson’s vetting. He noted Robbins and Collard had both said they were not unduly influenced, adding: “I believe both of them.”

McSweeney, when he gave evidence on this point, was also at pains to point out the different types of pressure. Reverting to metaphor, he said: “There is a world of difference between saying to a taxi driver, ‘I am late for a plane,’ to, ‘Can you break all the red lights and go speeding?’”

The committee chair, Emily Thornberry, could not resist an interjection at McSweeney’s reference to “red lights”. She referenced the now famous two red boxes on Mandelson’s vetting file. These were the boxes ticked by the vetting officer, signalling Mandelson posed a “high” overall concern and recommending “Clearance denied”.

Both Robbins and Collard, she pointed out, testified they did not personally see Mandelson’s vetting file, or the two red boxes, when they decided to grant Mandelson clearance. Both officials said they instead relied on briefings that said UKSV regarded Mandelson’s case as “borderline”.

“So both of them missed those red lights,” she said. “Is it not because of pressure being put on them?”