WHAT better occasion than a buck’s fizz breakfast for making up one’s mind about Boris Johnson? Genius or idiot, or both? Could he really be some kind of authentic political savant, or is the posh bumbler of the popular imagination entirely a self-creation? Some have called him a pretender to the Tory throne, and perhaps that word, pretender, is more apposite than is usually intended. In other words, is Johnson, who has just turned his hand to fiction for the first time, his own greatest character?

To find out, I have arranged to meet him in Scotland. He is spending a few days here as a morale-booster for the Scottish Conservatives. Today, he will meet the Tory faithful of Edinburgh South, who have each paid £15 for the privilege.

We are in a house so grand the obelisk on the lawn looks as humble as a birdbath. It is 10.30 in the morning and the atmosphere, in symphony with the champagne, fizzes and pops in expectation of his entrance. The Tories are generally getting on in years, but there is a sizeable contingent of young folk here, courtesy of Edinburgh University Conservative and Unionist Association (EUCUA).

For fledgling Tories, Boris is their Brad, their Britney, the bright star who makes Conservatism that bit cooler. And yet they do not seem entirely starry-eyed. Morgan Sobotka, 20, is unimpressed by his role as shadow arts minister, wryly noting that, “He doesn’t have to do any hard maths.” John Moffat, also 20, believes that Johnson has the air of a “permanent backbencher”.

By now, the man himself has arrived and is working the room. Although he is not particularly tall, it’s easy to follow his progress through the crowd, that great vanilla head bobbing like ice-cream in soda. He is wearing a grey suit and a blue tie covered in little swallows. The Conservatives swoop after him in great migratory patterns. He is presented with an EUCUA polo-shirt bearing the legend, “We shall fight them on the beaches”, and is asked to sign a T-shirt with his face on it and the words, “The World’s Favourite Tory”.

Eighteen-year-old Marianne Pickles, here as a raffle-winner, stands beside Johnson while someone takes a photograph. Afterwards she says, “I’d seen him on Have I Got News For You and Room 101 and he seemed a nice guy. I haven’t decided what political persuasion I am, but it was only £3 to meet him. When we were talking to him, he didn’t seem too interested, though.”

After a bit, Johnson gives a speech. It is vintage BJ; he makes a big thing of being muddled but is actually pretty coherent, he uses terms both obscure (“recrudescence”) and invented (“left-wingery”), and espouses traditional Conservative values, broadly that fox-hunting is good and tax is bad. He concludes with this cri de coeur: “I urge you, if you can, to go next door and look at the picture, the campest painting I have ever seen. It’s the translation of Byron into the heavens, where he is received by various naked putti. That’s what we want to happen to Tony Blair! May he be raised skywards!” He exits to the sound of massed huzzahs.

I follow. The idea is to interview him en route to Lesmahagow, where there is a lunch being given in his honour in the function room of a retirement home. I had imagined the two of us sprawled out in the back of a Bentley, but it emerges that we are to be driven there in a Renault Clio, a shocking choice of vehicle for this famous Eurosceptic; Johnson vexingly plumps for the front passenger seat, while I chew my knees in the back. We va-va-voom our way out on to the main road.

It’s tricky interviewing the back of someone’s head. I am reduced to gauging his reactions to my questions by the inflections of his voice, so plummy it ought to be emanating from a barrel worn round the neck of a St Bernard, and the shape of his mouth, glimpsed in the passenger-side mirror; it is probably the first time Johnson can truthfully be said to be speaking from a left-wing perspective.

As well as being the MP for Henley, and member of the shadow front bench, Johnson is editor of the Spectator and a columnist for the Daily Telegraph. He is 40 years old, has four children and recently published his first novel, Seventy Two Virgins. He is fairly cheerful about the book. “Bits of it are all right,” he says, and is keen to point out the “uncanny similarities” between his plot and the recent invasion of the Commons by pro-hunting protestors. He missed all the hoo-ha because he was on his way to be interviewed by Richard and Judy.

His appearances on popular television shows have added greatly to his public image as a dishevelled shambler. Most journalists conclude that it’s all an act, and offer as partial evidence the fact that he doesn’t even use his real name, which is Alexander Boris de Pfeffel Johnson, that he has created “Boris” as a kind of hustle. The trouble is that if it is an act, then it isn’t working because everyone thinks they can see through it and believes he must be secretly smart and ambitious. But if it isn’t an act, then he has a problem because, if he can’t change, he is always going to be seen as more comic turn than serious politician. So which is it?

“Well,” he says, humming and hawing, “we are all self-invented to some extent. Frankly, honestly, it’s now too late to try to invent anybody else. It’s exhausting. In so far as I’m an invention, this is the best I can do.”

Yes, but you are aware of those aspects of your personality that the public like. Do you amplify those in order to be more persuasive?

“Right. Well. I suppose so. I find the more unpersuasive I am, the more I persuade people.”

We are passing through Penicuik. Suddenly Johnson gasps. He has spotted something. “Why is the Belgian flag flying in the middle of … where are we? It’s the General Consulate of Belgium! Isn’t that astonishing?” He spent years working in Brussels as the Common Market correspondent of the Daily Telegraph, honing his Europhobia on the whetstone of legislation to do with standardised condoms and the like.

In his collected journalism, Lend Me Your Ears, you can read acres of copy devoted to criticising Europe, much of it beautifully written. One of the most fascinating things about Johnson is that his writing is controlled and eloquent, but his public appearances are a fugue of digression, mumbling and false starts. He is Jeeves when he writes, Wooster when he talks. “When I’m speaking,” he explains, “I find that every word begs to be followed by a huge organogram of different words. A flow chart. I start a sentence and I don’t know how it is going to end. Sometimes, while I am talking, my brain short -circuits and I can’t decide which lane to go down.”

As if on cue, David the driver changes lanes. We pass a sign. “Peebles,” says Johnson, gently rolling the word on his tongue as if it were an exotic canapé. “Biggar.”

Throughout the journey, he has been periodically taking and making calls on his mobile phone. Now he begs leave to make another. It’s annoying, but perhaps it is some grave matter of state. Who am I to stand in the way of the nation’s business?

“Hello?” he says to the phone. “Yes, I think we should get Sebastian Faulks. We need an umpire, and I don’t think he’s terrifically keen to play. We’ll have to work out who is going to be captain.” He pulls a piece of paper from his pocket and starts reading out names. “I think we should try to get there about 12.30 and have a team talk and some press-ups.”

This goes on for about 15 minutes. It is quite unbearably rude, so I bowl slightly tougher questions. Did you make up the story about Tony Blair’s chief of staff Jonathan Powell telling you a Scot would never be Prime Minister? “That story is entirely true.” Does it cause the Spectator to lose credibility that its publisher, Kimberley Fortier, has been having an affair with David Blunkett? “I don’t know the details of that relationship,” he fudges.

We talk about sex. The Spectator has been much associated with dirty deeds of late, thanks to various scandals. But now Johnson says that The Spectator office “resembles an Iranian madrasa in its spirit of contemplation and scholastic detachment”.

Johnson has himself become something of an unlikely sex symbol. The Erotic Review even featured him in their gods and goddesses issue last year, and he is regularly named as a contributor. “I contributed a drawing which I later tried to withdraw,” he says. “It was a tasteful rendering of a young lady and a horse.”

By the time we get round to talking about this, Johnson is clearly fed up being interviewed, and looks very glum in the wing-mirror. “I tell you what, mate. I’m exhausted. How long has this piece got to be?” Two thousand words, I tell him. “Seriously?” he asks, aghast.

The truth is that I’m feeling pretty car sick, exasperated with his whining, and bored of looking at the hair littering his shoulders like new-mown hay. I thought he was supposed to be a smooth media operator? He is the only Tory MP to keep an online blog and was recently profiled in Vanity Fair, an article which began by asserting that he was a future prime minister; you’d think he would be a bit more gracious with the press. I tell him I have a few more questions and he agrees to answer.

Are you religious? “Aaaah … aaaah … I don’t know. I find it very difficult to talk about. It always comes out wrong. Ummm, ummmmmmm. Aaaargh. I don’t want to talk about it, to be honest.”

I say nothing. Silence fills the car. “I suppose I am religious, yeah,” he eventually says, “but in a pretty despairing way. I have a lot of problems with it. I don’t find faith very easy. It comes and goes. It’s like Magic FM in the Chilterns. Sometimes the signal’s stronger than at other times.”

He attends Church of England services, and claims that his faith does not influence his politics, but his political thinking does have a mushy New Testament texture. “I think very often socialists are endlessly disappointed by the fallibility of man, and want to perfect our species and iron out kinks,” he says.

“For instance, they dislike the fact that someone can enjoy hunting. They have a revulsion against that state of mind. There’s something very intolerant about left-wingers, generally. You should glory in the imperfections of man. It’s a mistake to try to sandpaper off every flaw.”

Soon after this, the interview fizzles out. Johnson is far more interested in talking about Aristotle with David. When we arrive in Lesmahagow, he bids me farewell and apologises for drying up. “I’m a bit tired. Don’t know how I’m going to get through this lunch. Have a drink, I think.”

And with that, he shuffles off into the retirement home, where refreshments and obsequiousness await.

It has been said that Johnson has charm the way some people have perfect pitch, but if that’s so, he has failed to strike the right note with me, and by the time I leave him the scales have fallen entirely from my eyes. He has been arrogant, truculent and rude, and I would rather have spent time with that other famous Tory blonde, Ann Widdecombe, which is really saying something. I hope he has some more champagne at lunch, because the whole loveable buffoon shtick is beginning to fall a bit flat.