Donald Macintyre is a freelance journalist.  He is a former political editor and chief political commentator  for the Independent newspaper and the author of “Mandelson: And the Making of New Labour.”

It’s become commonplace in London to say the scandal surrounding former ambassador to Washington Peter Mandelson, which is so profoundly threatening Prime Minister Keir Starmer’s leadership, is the worst since the 1963 Profumo affair — when the then-Secretary of State for War was found to be sharing a lover with a Soviet spy. And the situation’s escalated even further, now that Scottish Labour leader Anas Sawar has called for Starmer to go.

Indeed, there are striking similarities between the two cases: In 1963, the already-weakened premiership of Harold Macmillan was damaged to the extent that some of his own MPs were calling for him to go — just as is the case with Starmer. And much like Profumo had lied about his fatal association, Starmer said Mandelson did the same when it came to the depth of his relationship with convicted sex offender Jeffrey Epstein.

When the exact circumstances of Mandelson’s appointment as ambassador — and what seems to be the perfunctory vetting process he went through — come to light, other parallels may surface as well. Namely, the question of whether Starmer personally looked Mandelson in the eye and demanded to know the truth in a face-to-face meeting rather than leaving that to others, like his now-departed Chief of Staff Morgan McSweeney and the intelligence services — something Macmillan was widely criticized for not doing in 1963.

The main difference between these two scandals, however, is that Profumo lied not only to his colleagues but to Parliament. When former Prime Minister Gordon Brown burst into the current dismal saga, he demonstrated what a principled Labour big beast really looks like, effectively serving notice that Starmer is on borrowed time to fulfill his mission to clean up politics.

And one of Brown’s pertinent suggestions is especially on target: charging a Commons select committee with holding pre-appointment hearings, including with senior diplomats.

The former prime minister persuasively argued that had this overdue reform been in place, Mandelson would never have gone to Washington in the first place. For one, an American-style parliamentary interrogation would have been far more adversarial than the vetting Mandelson actually faced. And had Mandelson somehow persuaded MPs not to veto his appointment in that scenario, he would only have been able to do so by lying to them — which, ironically, might have given Starmer some cover. For if Mandelson was prepared to lie to Parliament, which is still a radioactive offense in British political life, surely he would lie to anybody.

This makes an irresistible case for Brown’s proposed reforms. But even if Starmer presses ahead with them at the speed the former prime minister desires, it will hardly be enough to let him off the hook any more than the resignations of McSweeney or No. 10’s Director of Communications Tim Allan have — especially now that Sarwar is the first senior figure calling on Starmer to go. And the prime minister still has to confront the question why, holding as he does the job where the buck is supposed to stop, he went ahead with the Washington appointment when he already knew Mandelson had consorted with a sex trafficker?

As it unfolds, the scandal has two separate aspects: Mandelson’s Washington appointment and his leaks to Epstein when he was Brown’s de fact deputy between 2008 and 2010.

On the first count, Mandelson’s leaks to the disgraced global financier — not to mention his remarkable suggestion, which we now know was acted on, that JP Morgan “threaten” Chancellor Alistair Darling over bankers’ bonuses — are indefensible, even if Epstein hadn’t been a serial sex offender. To that end, then-Permanent Secretary to the Treasury Nick Macpherson’s recent statement — that there were suspicions investment banks had an inside track but the extent of it is “rather breathtaking” — is a classic civil service understatement.

Mandelson had enough Cabinet-level experience to know his communications with Epstein violated all protocols of government. Or, as one of Mandelson’s fellow peers put it, suggesting he was a “chancer” like  former Prime Minister Boris Johnson: “Boris probably doesn’t know the difference between right and wrong. Mandelson probably did but suppressed his knowledge far more than any of us realized.”

There was every sign of cynicism as well as closeness in the McSweeney -Mandelson relationship. To take just one example, McSweeney may not have invented the idea of Starmer campaigning for the leadership on a left-wing ticket in 2020 he knew he would never implement, but he certainly signed off on it.

Once Starmer got into government, all this changed, of course. It’s now widely accepted that even though McSweeney’s general-election-winning strategy may have been as brilliant as Starmer repeatedly said it was, the prime minister’s whole operation — which McSweeney was very much a part of — was far less prepared to govern than his Labour predecessors Brown or Tony Blair. Hence the baker’s dozen of embarrassing U-turns, and the all-too-widespread public confusion as to what Starmer truly stands for.

But there’s something else: Like his mentor Mandelson, McSweeney’s instincts were to steer the government to the right on so many policy issues. Whether that be on immigration — with the distinctly dubious strategy of trying to stave off the threat from the right-wing populist Reform UK party by being more like it — or the disastrously half-baked scheme to cut welfare benefits for the disabled without a comprehensive (and undoubtedly necessary) welfare reform plan. This is part of the reason behind the parliamentary Labour Party’s current unrest, especially as it was accompanied by the control-freakery of disciplining dissident MPs.

However, none of this explains how Starmer  — with, admittedly, next to no experience of party politics compared to his two predecessors — subcontracted the Washington embassy decision to McSweeney (and the vetters), as he appears to have done on so many other issues. I was even told by two well-informed sources, who were granted anonymity to speak freely, that National Security Adviser Jonathan Powell had warned Starmer the Mandelson appointment was potentially dangerous. But clearly it was McSweeney’s advice that prevailed.

As the Cabinet rallied around Starmer in the face of Sarwar’s intervention, and after  an impassioned rallying call to his MPs last night, Starmer has  survived the immediate crisis. But the reprieve may only be temporary. With  a crucial by-election less than three weeks away — and local, Scottish and Welsh elections in May — Starmer can only hope the well-justified  fear of some MPs that the party would be torn apart by a leadership contest will see him through for now. As  former Labour Minister Dame Margaret Hodge said yesterday, the government is in a “heck of a lot of trouble.” And without a truly major reset, that’s going to be true as far ahead as anyone can see.