In the late 1800s, the boxing and wrestling scene of east and south-east London was going through a transformation, and if you are genuinely interested in that, I cannot recommend enough the work of the historian Sarah Elizabeth Cox. If, on the other hand, you are more interested in the fashioning of political analogy, it is this: boxing starts out a legit contest between boys and men trying to render one another unconscious; then it morphs into strongman pantomiming, with one amazing boxer in the ring and have-a-go heroes trying their luck; then it starts to lean in to its showbiz elements; and after that it’s chaos. The strongman is suddenly wrestling a donkey called Steve (this really happened). People are slicing lemons with swords in the interval. It’s all a terrible stain on the noble sport, and yet it looks revivified, because suddenly every idiot in town thinks he can have a go.

Which is more or less what’s happened to the office of prime minister, and I’m going to go out on a limb here and say that this, unlike everything else to befall this stricken nation, is not Keir Starmer’s fault. Amazed as I am to even type this, it’s not Boris Johnson’s fault. It started with David Cameron.

His justification for seeking the highest office was: “I think I’d be rather good at it.” But what is often forgotten in that narrative – of an indolent, entitled youngish man who was raised to look at complicated systems and think, “Who better to steward that than myself?” – is that his real triumph was at the Tory conference in 2005, when he came off as the breath of fresh air needed by a party that had been uncharacteristically out of power for nearly a decade. Though you know what they say about Conservatives: they’re always in power, only sometimes in office. Or at least, that’s what they used to say, in the old days of wrestling … sorry, Westminster.

Cast your mind back to 2005, unless you want to stay cheerful, in which case go and do literally anything else. The other candidates were Ken Clarke, who sounded sane and reasonable, and was therefore dead in the water, the party having already had enough of all that; Liam Fox, who made a racist and sexist joke about the Spice Girls for which he later apologised (go look up his joke, unless you want to stay optimistic); David Davis, who actually won the most votes in the first round, but didn’t tip the 50% and therefore had to go to round two; and Cameron himself.

At the risk of sounding Facebook-nostalgic to the point of being a Tory member myself, this is not how leaders of political parties used to be chosen: “Please, not any of these candidates we know. Let’s give that guy we don’t know a shot. He looks quite energetic, or at least pink.” Before 2005, a leader would have had a rich political hinterland. She or he would have launched from a power base, would have an origin story going back to a definable political wing of their own party, would have been forged in the fire of the harshest imaginable competition. Cameron had a stint in the early 90s helping to define (John) Majorism. QED.

What was to stop anyone, after that, chancing their arm? Was it really so outlandish for the next battle to be between Theresa May and Andrea Leadsom, whose fundamental political difference (if I recollect correctly) was about whether it was sexist to critique your opponent for her childlessness (why yes, it is)? By the time Johnson had flamed out for personal failings that had been visible from space, for decades, it would have been almost rude not to have a go, a pattern that deepened into an elemental truth by the time of Liz Truss. Her only distinction – and you can’t take this away from her – is that she didn’t even spend enough time in office to do any damage, yet managed to do an awesome amount anyway. Can there have been a single Tory MP who didn’t, on some level, think, “Well, I couldn’t do worse that that”?

And now here we are, Labour going through a strikingly similar back-and-forth psychodrama of: “Not this guy; but there’s no one else; but not this guy; but … etc”, and you start to look at people who aren’t MPs, people who aren’t even politicians, and think, “I don’t see why not.” But here, unlike music-hall wrestling, politics hits the buffers of reality. You can’t manifest a David Attenborough prime ministership, with Emily Maitlis as foreign secretary, by force of will.

Zoe Williams is a Guardian columnist

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