The Scotland comments are just the latest grenade Johnson has thrown at himself

Back in the summer of 2019, when the police were called to a flat in south London, it was speculated that merely placing Boris Johnson under effective house arrest would not necessarily be enough to stop him destroying his own bid to become Tory party leader. He appeared to be more than capable of destroying it even from inside the house in question.

And so it is again. Naturally, day one of Boris Johnson’s big “relaunch” was the one in which he had to announce he was self-isolating for two weeks. And day two would be the one where he broke the union from the comfort of his own laptop.

A total of 67 Tory MPs were on the zoom call on Monday night when he breezily announced that devolution had been “a disaster for Scotland”, and “the biggest mistake Tony Blair ever made”. (Not quite the biggest, no, no matter how many times Blair might have begged for it to be so, in conversation with the bedroom ceiling at 3am.)

In his final days in Downing Street, it has been reported that Dominic Cummings developed an extraordinary habit of pulling a pin from an imaginary grenade and throwing it over his shoulder as he left a room. Bizarre, one might think, but at least Cummings’s little flourish involved him exiting the scene before the imaginary explosion. Johnson is setting off bombs without remembering he’s not allowed to leave the house.

It took Scottish Conservative leader Douglas Ross a matter of minutes to have to disown his own prime minister, quite possibly for the eighth time that day, though no one’s counting. One wonders whether Ross is wondering whether he should have thought a little harder about what might be in store for him, when the Tories’ best and brightest prospect in years – Ruth Davidson – worked out that on Johnson’s watch her job would be impossible, and so quit.

It is unfortunate, both for Johnson and the mere rest of us, that the prime minister appears psychologically incapable of continuing as a kind of columnist on his own ineptitude. The sheer range of things that will bring him down in the end is so vast it is unlikely ever to be possible to measure how much his ill-conceived, tossed-off thoughts have cost him.

The breezy lie about Nazanin Zaghari-Ratcliffe “training journalists” in Iran, for example, will dog him to the end, even if the price he pays will always be a fair bit lower than hers.

It’s quite conceivable he really believes this stuff doesn’t matter. That perhaps the public like a politician who is prepared to just say whatever they like, and for whom words are not the precious currency they ought to be, but chicken feed to be spaffed up a wall.

I can recall a room recoiling in horror when, as foreign secretary, he made a little joke about having to clear up the dead bodies on the beaches in northern Libya. But in the end, did it really cost him anything?

Other people, even people with a very low opinion of him, will still find themselves having to come out and atone for his various messes. On the radio on Tuesday morning, Sir Malcolm Rifkind had to do his level best to ascribe to Johnson the words he should have said, or perhaps meant to have said, that devolution had indeed been a disaster for Tony Blair, because it had come to cost Labour so many seats in Scotland.

It was patiently pointed out, however, that this isn’t what Johnson did say. He said simply that devolution had been a disaster, that Scotland appeared to be incapable of electing a party that would govern in its best interests, and as such it really couldn’t be trusted to govern itself.

He remains, as ever, Nicola Sturgeon’s favourite ever Christmas present. The embodiment both of Brexit and of the kind of Old Etonian Toryism are found to be so repulsive in Scotland that support for independence seems to grows by half a per cent or so with every passing week.

And all this before the cold, grim realities of Brexit have even begun.

It will be no surprise to anyone if trademark Johnsonian indolence comes to break the union. His is the story of a kind of coprophagan King Midas, where all he touches turns not to gold but to something rather different.

Where his handling of coronavirus ranks in the grand scheme of it all is too early to say, but it is regularly and accurately foretold that Scottish independence would make Brexit look like a mild hiccough. His grandest disaster is quite possibly, probably even, still to come.