In Westminster on Wednesday, two unfamiliar things happened in the space of a single day: there was a moment of unadulterated good news, and then Boris Johnson declined to twist the truth to take an easy swipe at the European Union.

First things first. Obviously the government claims it has good news all the time, but usually it turns out to be “Australia-style good news”, or, as it’s more properly known, bad news.

So on learning that Britain was the first country in the western world to approve a Covid vaccine, the muscle memory braced for the next sentence, which would reveal that because a minister had signed a form in the wrong colour ink, we all had to have the drug injected into our eyeballs, or queue up for it, spaced two metres apart, outside a pharmacist in John O’Groats. Maybe we, like the drug, would have to be cooled to minus 70 degrees before we could take it. 

But no, as we cautiously circled the news and prodded it, it seemed to all be good. The vaccine works, it is safe, we have supplies of it. People will start getting it next week. Rejoice! Rejoice! 

So, the government had done a good job. This government being what it is, though, ministers moved swiftly to muddy the waters, with Health Secretary Matt Hancock claiming the regulator had only been able to move so quickly “because of Brexit”. If that sounded unlikely – after all, if Brexit means anything at all, it means things moving very slowly, especially as they approach Dover – it turned out this was an Australian-style claim, or, to put it another way, wrong. 

Is the real Johnson imprisoned in an attic at Chequers?

But saying things that aren’t true about Brexit is certainly not an unfamiliar thing for this government. Leader of the Commons Jacob Rees-Mogg swiftly joined in. Familiar, too, was the next step in the process, where the regulator shot the idea down, pointing out that they were, in fact, still operating in vassalage to the hated European Union overlords, but had nevertheless been able to do their job, and do it well.

All of this, as readers will know, is the sort of thing that happens in SW1 whenever there’s a “y” in the day. Ministers say good things are the result of Brexit. Lib Dems say actually bad things are. Labour stay quiet, hoping the storm will one day pass.

But then something very odd happened. At his evening press conference, the prime minister was offered the chance to affirm that the early vaccine was a “Brexit bonus”. Remember, this is Boris Johnson. The fellow with the bus. Messy hair, desk covered in angry letters from the Statistics Authority. That one. Former Telegraph columnist whose own newspaper argued, while paying him £5,000 a piece, that no reasonable person would expect him to be accurate. Some politicians have a loose relationship with the truth; Johnson met it once three decades ago and has been refusing to return its calls ever since.

And yet that very same Boris Johnson, watching the gentlest of underarm balls rising neatly towards his bat, let it go past. The credit for the swift arrival of the vaccine, he said, belonged to the people who had worked to get it through the approval process. 

Perhaps he had misheard the question, his mind elsewhere. So he was asked again, and again he refused to say it. Boris Johnson, a man who has been sacked from two different jobs for lying, was, if not insisting on a point of accuracy, then at least declining to join in the general inaccuracy. 

MPs have worried for months that the prime minister is suffering from lingering Covid effects. I’m now more concerned that he might have been replaced by a lookalike. Is the real Johnson imprisoned in an attic at Chequers, forced to wear an iron mask to conceal his true identity from his jailers, all his attempts to escape thwarted because every time he manages to steal a pen and paper, he uses them to draw a rude picture or write a limerick about a girl from Nantucket?

There is another theory, that we are witnessing the Allegrification of Johnson. This argument goes that Allegra Stratton, the prime minister’s new director of communications, is urging him to play less to the gallery and instead make himself into a serious figure. 

If so, it’s a Herculean task. But it is of course inevitable that if Johnson’s government suddenly decided that it was going to be characterised by painful honesty about Brexit, Matt Hancock would be in the final group telling lies. He never gets the memos.