Theresa May has only one job left as prime minister – to finally kill off Boris Johnson's political career

In whatever time she has left, Theresa May faces two major challenges.

One seems undeliverable: at this moment, you’d have to be on a fairly spectacular acid trip to picture her finessing any Brexit through the Commons or past the country.

The other, however, looks more achievable. This PM must ensure that Boris Johnson is not the next.

People laughed at Boris when his ambition first became obvious. But as with Bob Monkhouse, helmsman of Family Fortunes long before Stanley Johnson monetised the bloodline on I’m A Celebrity, they’re not laughing now. This is lethally serious.

If only there were a recent precedent of a metropolitan elite underestimating a mendacious, egomaniacal chancer with an arrestable offence masquerading as a hairdo? In its absence, we’re on the cusp of a leadership challenge from someone whom a more serious democracy, such as Toytown, wouldn’t entrust with the post of undersecretary of state for cleaning PC Plod’s helmet.

How close he is to launching the coup, and how viable it would be, is unclear. So often has “Baby Trump” – I know it sounds like tautology; just think of a toddler cuddling a Tiny Tears doll – knocked on the No 10 door and run away that it’s tempting to dismiss this latest intervention as another round of Knock Down Ginger.

This one, confided to readers of his Telegraph musings, seemed deranged even for him, as he delved into professional wrestling for a wicked conspiracy. “The whole thing is about as preordained as a bout between Giant Haystacks and Big Daddy,” he wrote of Brexit. Younger readers may know nothing of those British precursors to Hulk Hogan and The Rock. But, thanks to WWE, they will be familiar with expertly choreographed wrestling bouts with fabricated outcomes. Does that sound like Brexit to you? Does anything here look meticulously rehearsed? Do you discern the hint expert choreography in all the punch drunk staggering across the Brexit ring?

There’s method in his madness, of course. Step one, when you’re trying to incite the headbangers’ rage, is to feed the addiction to the sense of betrayal, which is the drug of choice for those at both extremes of the mainstream political spectrum. Whether it’s Corbyn cultists dreaming of deselecting ideological traitors, or Brexit ultras fantasising about the purifying power of the no-deal bonfire, they live for it.

Boris knows this. If anything has the flavour of wrestling moves in this waking nightmare, it’s his ritualistic use of the language of surrender to put May in a half nelson from which she cannot wriggle free.

Boris isn’t a half Nelson, or a quarter Churchill. Where they rescued their country, he would burn it for power. He’d burn up galaxies for that. But he is a danger, and if and when the leadership challenge comes, it’s a sure thing the threat of deselections will cross the floor of the House. Tory constituencies will come under pressure to ditch MPs who refuse to back the standard bearer of the Brexit far right.

If Boris gets into the two candidate runoff against a “moderate” such as Sajid Javid or Jeremy Hunt, he wins. This scenario being at least as mortifying to May as to anyone else on nodding terms with sanity, her last and greatest duty is to stop Boris even at the cost of her own political life.

For a vicar’s daughter, the literary reference point is Judges 16:29, in which Samson brought down the temple roof to destroy the Philistines as well as himself.

But sticking with wrestling analogies, a more recent episode from western fiction will suffice. I refer to Sherlock Holmes taking out Moriarty at the Reichenbach Falls. It is true (spoiler alert) that due to popular demand, Conan Doyle resurrected Holmes. “We tottered together upon the brink of the fall,” he tells Watson in The Empty House. “I have some knowledge of baritsu, or the Japanese system of wrestling, which has more than once been very useful to me.” But originally, in The Final Problem, Holmes calculated the cost of his life as a bargain to take Moriarty down with him and save his country from its worst menace.

Accepting that delivering a strong and stable Brexit – or any Brexit – is plainly beyond her, May must identify stopping Boris as her final problem. Downing Street statements about his lack of new ideas won’t cut it. It’s long been apparent that he doesn’t have any old ideas.

She cannot rely on the common sense or decency of her MPs. The majority know Boris for what he is, and plenty actively hate him. But under duress from local parties, with opinion polls citing him as their best hope of holding their seats, they are capable of sending his name to the members. You need only glance at the cowardice of congressional Republicans to appreciate the career politician’s capacity for indecency. You need merely recall that 15 years ago Tory MPs put Iain Duncan Smith into the final two to gauge their common sense.

God knows what May’s solution to the Boris problem might be. It could be timing her departure for maximum impact on his prospects and making a resignation statement itemising her fears in brutal detail. If it came with the risk of doing time under the Official Secrets Act, or worse still losing the automatic peerage, she could declassify his MI5 file. That ought to do it.

Whatever it takes, she must know, if she didn’t before, that she and Boris are engaged in a deathly grapple on the edge of a terrifying abyss. If she can find a way to take him over it with her, she wouldn’t come back. But she would leave with honour, dignity, and the eternal gratitude of a nation that would at least be able to know itself as slightly less terminally gullible than the United States.