Today Boris Johnson becomes Britain’s prime minister.

But who is he, what’s he like and what can we expect?

By weird coincidence, he happens to be the second prime minister with whom I was friends at university. And the first reassuring news I can bring is that he is going to be a considerable improvement on his predecessor-but-one, David Cameron.

To understand their differences a good place to start is their attitude to the exclusive education they were lucky enough to enjoy.

Both went to Eton, where they learned – among other things – that they were born to rule. But where for Cameron this was a stigma – an embarrassing impediment to his attempts to pass himself off as the people’s prime minister ‘Dave’, for Boris it’s all a jolly wheeze, something to be celebrated at every turn with old school slang and Latin epigrams and a self-consciously posh, fruity accent. (As a recent profile put it: “Johnson’s rare gift is to combine unabashed elitism with popular appeal.”)

In other words, one takes the career-safe, conventional, hand-wringing, guilt-ridden, damage-limitation approach to having been born with a silver spoon in his mouth.

The other couldn’t give a stuff: you are who you are; what matters is what you make of it; and anyway what’s not to like about having had the best education money (or in Boris’s case, scholarship) can buy?

Cameron was a managerial, Nanny-knows-best prime minister, whose main aim was to stay in power for as long as possible by not rocking the boat.

Boris, by contrast, is a mischief-maker and a fun-lover. Whatever else goes wrong during his time in office, of one thing we can be sure: it will be royally entertaining – like the Restoration of the libertinous, libidinous court of Charles II after years of dreary puritanism.

I like Boris. He’s funny, witty, scatty, shambolic with a very sharp brain whose cogitations you can almost see as he talks to you. Partly he’s sussing the situation, partly – like a lot of wags – he’s waiting for the entry for his next bon mot.

He also has a vulnerability – a forlorn, little-boy-lost quality which makes you want to protect him. (I’m sure this is part of the reason why women find him so attractive). I remember my wife and I consoling him, two or possibly three years ago at the Spectator party when his career seemed at its lowest ebb and Boris looked wounded, hunted, shattered. With hindsight, I now realise I was watching the equivalent of Churchill in his Wilderness years: Boris biding his time, caught in the act of reculer pour mieux sauter. In private, I suspect – not that I’ve ever seen him in private: he saves those moments for his wives and girlfriends – he’s artistic, sensitive; but in public there’s always that carapace of bluff jollity.

If you want deeper psychological insights into Boris, I highly recommend Tom McTague’s superb, thoughtful, and remarkably apolitical profile in – of all places – The Atlantic.

It has many great moments, such as its account of Boris’s encounter with Will Smith:

Smith was the star guest at City Hall in May 2013 at the beginning of Johnson’s second term as mayor—a high-water mark in Johnson’s popularity, having overseen the London Olympics and won reelection the year before. He had been cheered by tens of thousands of Londoners at an event just before the games opened, dismissing “doom mongers” like Mitt Romney who had suggested London might not be ready to host the Olympics.

Standing onstage together, Smith bounced a question from the audience directly to Johnson. “Mr. Mayor, who are your biggest inspirations?”

“Oh my God, arr, you, you mean apart from Pericles of Athens?” replied Johnson, flustered, before shouting, as if he’d only just remembered: “Aristotle!” The answer prompted Smith to note that Aristotle was, in fact, also a hero of his for Poetics, which is widely read by filmmakers. Johnson, not wanting to be outdone, countered that Nicomachean Ethics could have been called The Pursuit of Happyness, one of Smith’s movies.

“We have a lot in common,” Smith said to Johnson, wrapping up the incongruous exchange.

This is one of the reasons why Boris is going to get on so well with Donald Trump. Neither of them is a conventional politician; both are much closer to being celebrities than career hacks – which gives them the advantage of being beholden to no one.

Also, like Trump, Boris has a knack for driving his critics apoplectic. It’s odd that Boris should attract such vitriol: as Conservatives go he’s really not that ideological or indeed particularly right-wing – socially liberal, generally pro-immigration – so it’s a bit unconvincing that the Twitter hate mob should try to paint him as a Nazi.

I’m equally mystified by the loathing he gets from the right. Sure I see their concerns – that Boris, lacking many core Conservative beliefs other than a disposition towards liberty and free markets, may prove a flip-flopper or a cop-out or a Conservative-in-name-only.

I certainly wouldn’t rule out the possibility that he might gravely disappoint. If you go back through Boris’s writings you’ll find him contradicting himself on pretty much every subject so that it’s very hard to discern what he actually, genuinely believes in – if anything at all.

What scares me more than his lack of ideological backbone is his hatred of confrontation and his desire to be liked. I can all too easily imagine him handing out senior positions to Remainer has-beens from the old regime out of a vague sense that he owes them or that this will bring peace to a divided party – which it won’t, and will just undermine everything he needs to achieve. Also, he has been harping on quite a bit recently about One Nation Toryism, which is just a euphemism for more Heir to Tony Blair.

But I think all the people confidently asserting that he will be a disaster are speaking too soon. Sure it might be a canny way to cover your arse: “See! I told you he was going to be bad. I’m Nostradamus, me.” The truth is, though, Boris is so opaque, such an unknown quantity even to himself, that anyone who claims to know what’s going to happen next is talking bull.

So let’s just celebrate for the moment what we’ve got, keep our fingers crossed and hope for the best. Boris is a charismatic, entertaining, and positive figure who believes in Britain and who believes – as Churchill did – in sunlit uplands and a brighter future.

That seems to me a very good starting point for an excellent administration: the kind that could, with a bit of luck, some sensible decisions and a fair wind behind him do what Donald Trump is doing for America – Make Britain Great Again and drive his enemies mad as he does it.