Boris Johnson was furious. Fuming. Spitting mad. Fit to bust. He had just learned, just last night, that apparently there were people having parties in 10 Downing Street — 10 Downing Street! — during last year’s lockdowns. Worse still, when asked about it, people working there had said nothing had happened!

So he had come to parliament to set matters right. “I understand and share the anger up and down the country at seeing Number 10 staff seeming to make light of lockdown measures,” the prime minister told the House of Commons, where for weeks he has been making light of lockdown measures.

“I can understand how infuriating it must be to think that the people who have been setting the rules have not been following the rules,” the man who has spent months setting, but not following, rules went on.

He wasn’t finished: “I repeat that I have been repeatedly assured since these allegations emerged that there was no party and that no Covid rules were broken.” And who had given Boris Johnson those assurances? No less a person than the prime minister, Boris Johnson, who a week earlier, on that very spot, had announced that “all guidance was followed completely in Number 10”.

It’s a pretty sorry state of affairs. If Boris Johnson can’t trust the prime minister, who can he trust?

The problem, it seems, is that the prime minister has bad advisers. He’s on something like his third set now, but the advice continues not to be up to scratch. Now, he said, he was asking the Cabinet Secretary, Simon Case, “to establish all the facts and to report back as soon as possible.”

Scientists still haven’t found a way to stop transmission of a virus simply by briefing against it to the Daily Telegraph

Case, presumably, is a good adviser. It’s not clear whether he is also one of the “very well-respected civil servants and special advisers’ whom Johnson subsequently told us had assured him that all the rules had been followed at all times. Presumably not, though it would be really interesting to know who they were, given how bad their advice has turned out to be.

Case’s job is to investigate the 18 December party, which Johnson’s office previously told us hadn’t happened. Their position has now evolved, in that they can tell us that neither Johnson nor Case attended it, which rather implies it did happen. Although Johnson still held out that it might not have. In fairness, if I’d just heard that a bunch of my colleagues had been partying in my house while I was stuck upstairs with a baby, I’d be clinging to the idea it might not be true, too.

Keir Starmer was good. Not brilliant, not outstanding, but sufficient unto the day. He shut down Tory hecklers pretty effectively with the tale of a woman not visiting her dying mother over Christmas while Downing Street aides partied (or, possibly, didn’t). It is worth remembering, when you hear Conservatives denouncing Downing Street aides for laughing about their lockdown party that, this time last week, lots of Tory MPs were doing exactly the same thing. Jacob Rees-Mogg, the Leader of the Commons and a man who makes a great deal of his own gentility, joked about it in a speech days ago. It seems unlikely he will resign over this.

Johnson, on the other hand, was terrible, and it was only his second worst performance of the day. His press conference later would be so confused that the most coherent message out of it was that we can meet our colleagues in a nightclub but not in the office. He looked weary, looking at the ground and shaking his head whenever journalists or MPs asked him about things he’d rather weren’t true, the picture of a man who has lost track of what lie he told to who.

But he hasn’t lost his survival instinct. It was clear from the outset that staff were going to get thrown under the bus. The first to go, a few hours later, was Allegra Stratton, in a tearful statement outside her house. Why was she quitting over a party that she hadn’t even gone to? Had her Secret Santa gift been that bad? Maybe it’s like they say: if you had to resign over the Downing Street party, you weren’t there.

When Johnson returned to our screens later, it was for a press conference in which we learned that, two years in, scientists still haven’t found a way to stop transmission of a virus simply by briefing against it to the Daily Telegraph. He was speaking at the same time as Sajid Javid, the Health secretary, was telling the Commons the bad news. Since the summer, Javid has done his best to indulge the magical thinking of his fellow Tories, even going on TV to explain that friends can’t give friends Covid. Now reality had forced him to pick a side. From behind him there came a shout of “resign”.

Over in Downing Street, we were in a different kind of denial. “As far as I’m aware, we followed the rules on Dec 18 as well,” Johnson told the press, implying that Stratton had resigned over a party that not only did she not attend, but that hadn’t even happened. He and Case could have saved quite a lot of time if they’d just asked Stratton when she was giving her notice whether the party had in fact happened. But it’s easy to be wise after the event.

Or events. What about the party a month earlier that he had not only attended but spoken at, he was asked. If anyone had any evidence about that, Johnson replied, they should bring it to his attention. So that he can destroy it, presumably.

There will be more victims before this is over, people who went along with things that in other circumstances they wouldn’t have countenanced. Johnson seems to have that effect on people, tarnishing everyone he touches, leaving reputations destroyed in his wake.

Downing Street staff, seeing their boss preparing to sacrifice them to save his own skin, may wonder whether the real problem was that they had a bad prime minister.