A MODEST proposal. When teenage kids are lined up in school for their booster vaccines, medics should ask each child the following simple question: “Do you want to be prime minister when you are older?” Most of the youngsters, heads well screwed on, will pass on the opportunity to star as the main attraction in the live-action vivisection. There are, after all, other more ordinary ways to ruin your life.

But a small minority? A funny light will spark in the back of their eyes. Their shoulders will roll back. In their mind’s eye, they’ll begin to pick out silver numbers on a lacquered black door and imagine banks of cameras crackling like Catherine wheels. They’ll hear the ovation in the conference hall. These children, I would suggest, are children to be wary of. I know. I was one of them.

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In the interests of public safety and the better government of this country, I therefore recommend that any teenager admitting to this kind of political ambition should be exiled to Rockall to live out their days as a harmless gannet herder. There, these kings and queens of infinite space would do less damage than the stark- staring maniacs the British electorate – in its wisdom – seems inclined to hand power over to.

Contemplate all the leading figures in Theresa May’s divided cabinet – your Leadsoms and Hancocks, the Hunts, Raabs and Goves – and you know in your bones that each and every one of these squirming bags of appetites were teenaged dingbats marching around their schools with briefcases and serious expressions, proclaiming their ambitions to take over the world. University contemporaries remember a 20-something-year-old May telling them she wanted to be prime minister, and her petted lip when Margaret Thatcher was installed in Downing Street, going down in history as the first woman to hold the office.

In fairness, this isn’t a uniquely Tory phenomenon. You encounter similar characters in every political party in with a sniff of power. Wearing the slightly glazed look of Mormon missionaries, they clip around party conferences in suits, like satellites orbiting the great and the good, in the hope of falling into the favour of a powerful sponsor. In my day, when New Labour was in its pomp, you had your Labour Student drone. Today, the SNP has its fair share of ambitious young things describing a similar circuit around the party’s MPs and MSPs.

So I was unstunned to discover that the presumptive favourite to succeed May as Tory leader and prime minister has precisely this kind of origin story. According to Boris Johnson’s younger sister, Rachel, the juvenile Johnson didn’t fancy being a tabloid hack, an arms dealer or a City spiv.

“Whenever anyone asked him what he wanted to be, he would answer ‘world king’”, she remembers. “He thought that was a job that he could do, and he would fulfil every criteria.” Hoist the red flag. Fetch the boat and alert the kittiwakes. Rockall deserves a new inmate.

Like the phrase “he doesn’t suffer fools gladly”, the line that any politician was “raised in a very competitive family” reliably brings me out in cold sweats. It is more of a diagnosis than a description. Ambitious for what? To what end? To what purpose? And to whose benefit? Rachel Johnson says her older brother has “always been a competitor, right from the age of 14 months. He knows that life is a competition, and he always wants to be top.”

You might well think the idea of a one-year-old ablaze with restless ambition is just plain weird, but this pathology of the personality is – inevitably – presented as a unique merit of London’s former mayor. Yet more evidence that this great merkin is preordained by nature to be the First Lord of the Treasury this sceptred isle deserves. This kind of ambition is like a stomach, always famished however much it consumes, always aching for more, and more, and more. I profoundly mistrust it.

But unless his enemies in the parliamentary party can take him out, three years after Gove’s betrayal, Johnson’s unquenchable ambition now looks odds-on to propel him into Downing Street. Conservative leadership rules allow MPs to whittle leadership candidates down to a final two, who are then put to the Tory membership at large to make the final selection.

This week, YouGov polled Tory members about their thoughts on the key contenders to replace the stricken May. Johnson has surged ahead of all of the alternatives – 39% of party members have him for their first preference, 26 points ahead of his nearest competitor.

Whether the match-up is against Sajid Javid or Dominic Raab, Jeremy Hunt or Penny Mordaunt – take whichever contender you like – Johnson comes out as the winner in every calculation.

The National: Conservative Party leadership hopeful Sajid JavidConservative Party leadership hopeful Sajid Javid

Consider the context in which MPs will be drawing up their shortlist, and members will be backing their preferences. What lessons are the Conservative Party likely to take from their impending pasting in the European elections? Across the piece, the polls show the Brexit Party is cannibalising the Tory vote. May’s administration is tanking. The fact that the Labour Party seems in similar straights isn’t much comfort either.

Whether or not it does their cause any good with the wider electorate, whatever impact it has on their chances in a general election, sometimes political parties like to do something, you know, just for themselves. Inflicting a Johnson administration on the nation sounds just the ticket. It is the logical consequence of the – deeply mistaken – diagnosis that the problems of Brexit are essentially problems of personality.

To rip off J Michael Straczynski, British politics is obsessed with two questions when it comes to its politicians: “Who are you?” and “What do you want?” Always neglected is the third – much more important – question which any would-be politician should be confronted with: “What do you actually wish to achieve in the world?”

So consider this. In what sense would replacing May with the former foreign secretary bind the wounds of Brexit? What evidence is there that the Telegraph columnist is better placed than his predecessor to winkle out a workable version of Brexit which could reconcile his party’s conflicting demands? What evidence is there that Johnson has the ghost of a practical idea where to go from here?

Under the microscope, there’s nothing to speak of. There’s only a disgruntled Tory electorate, exhausted by detail, angry as hell, who think all they have to do is pick the big character and hope the finnicky detail gets stomped into something resembling good order. It’s a forlorn hope.

Closer to home, my bête noire Ruth Davidson’s political career has been characterised by a similar preoccupation with what she is, and what she wants. The Scottish Tory leader’s character lines are very sharply delineated. We know she wants to be first minister. But when we turn to that awkward third question – power for what purpose? – all of those clean lines begin to grow fuzzy. Despite the rigmarole Davidson makes about her hostility to Johnson, their political schticks have clear parallels.

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Ambition need not be toxic. A desire to shape the world around you for the better, to enrich the lives you cross on your way and to be enriched in turn, to learn, to experience, to challenge and expand your soul are all intrinsic goods. But that’s a world away from a thirst for position for position’s sake, a thirst which isn’t slaked by the getting of it and isn’t informed by any organising principle about what the hell you want to do once you have it.

Brexit Britain, under a Johnson administration? Life on Rockall’s starting to sound pretty sunny after all.