Media playback is unsupported on your device Media caption Comedian and actor Sacha Baron Cohen gives a rare interview as himself

Sacha Baron Cohen avoids the limelight - he prefers to let his comic creations do the talking. So I'm surprised to be offered an interview with the man himself. What's the catch?

"Which university did you go to?" asks Sacha Baron Cohen.

I'm taken aback. Not by the question per se, which is a fairly standard enquiry (dogs sniff bottoms, the middle classes compare education - the purpose is the same: to gauge status).

But it is extremely unusual to wheel it out, as Baron Cohen has done, as a conversation opener. It jars. And, paradoxically, it reveals more about the one asking the question than he or she can hope to gain from hearing the answer. I'm suspicious.

Baron Cohen is a clever man (Cambridge University, incidentally) who would not ask such a question without a good reason. Which is why I'm taken aback. Am I his latest fall guy?

It is unusual, too, to interview the comedian as himself. He has not previously given a formal interview to a British broadcaster, preferring instead to appear in character - Ali G, Borat, Bruno and now General Admiral Aladeen in The Dictator.

It's not as if his new film needs extra publicity. It has had some decent reviews and has been "tracking" well as far as advance box office is concerned. So I agree to the interview - offered at very short notice - with some trepidation. This, after all, is a man who has made his name by setting others up.

Image copyright Getty Images Image caption Sacha Baron Cohen in character...

By the time we meet, I'm in a state of heightened alert. He arrives with a small entourage. Bearded men in checked shirts spread out around the space in which our camera is set up and start to check everything out.

They behave like security guys, avoiding eye contact and any pleasantries. They're PR blokes, Baron Cohen tells me. And then three slightly calmer men, also part of the Baron Cohen posse, wander over for a chat. They, it transpire, are his writers.

His writers? What on earth are they doing at a press interview? I'm used to PRs and make-up artists being in attendance, but I've never known a group of writers to rock up before.

Eventually Baron Cohen emerges and we take up position on a hotel balcony one sunny afternoon in Cannes. He is chatty and likeable and constantly on the look out for the opportunity for a gag - but he is forever popping off to do something.

I wish I could relax and enjoy his company but I can't, especially when he smiles. That mouth, those teeth! It is Ali G. It is Borat. It is deeply unnerving.

I also wish he'd relax.

Image copyright Getty Images Image caption ... and as himself

"Should I wear my sunglasses?" he asks. "No Sacha, they'll make you look shifty."

"My eyes might stream."

"I'll tell you if they do."

And then, just when everything is set and we're about to start…

"I need to go to the loo."

Once again, my suspicions are raised. The writers are surely poised, the cameras hidden: the trap set.

He returns, sits down, and puts his mic back on.

I ask why, when at Cambridge, he wasn't part of his generation's Footlights.

He has just started on a story about how he only chose Cambridge in order to be in the Footlights, but was refused entry because his humour didn't chime with the tradition set by John Cleese et al ("there were lots of jokes about cricket matches," he says), when he picks up a glass of cola and takes a drink.

This ruins the shot. We have to start again. Is it a wind-up?

What Sacha's doing next Cast as Monsieur Thenardier in film version of hit musical Les Miserables, due out next year

And as Freddie Mercury in biopic of Queen's flamboyant lead singer

No, I don't think so. He seems genuinely nervous and inexperienced at being interviewed. Hence the posse - safety in numbers - and the unusual question about which university I went to. (I didn't - "What!" he exclaims, "I thought everybody at the BBC went to Oxbridge.")

Of course he's unduly nervous. Rather like doctors who tend to become hypochondriacs because they see ailments at their most acute, so Baron Cohen is used to interviews in which he seeks to make fools of his subjects.

Once he relaxes, he's open, funny and revealing. He's willing to talk about anything I ask, even - such as his opinion of the United States - when he's slightly contradictory. Unsurprisingly he's at his happiest when telling an anecdote that allows him to slip into one of his characters.

So why has he come as Sacha Baron Cohen?

"When we were doing The Ali G Show and from then onwards, I realised that the moment I went on air and started talking about 'oh yes, I set people up' and there were photos of me, there was a chance the interviewee would withdraw consent.

"It was to protect the comedy and protect the movie. Now I don't really have to that; this [The Dictator] is a different sort of movie."

But why now? In common with all performers, he likes attention, but he gets plenty of that anyway.

Maybe he just fancies giving it go.

Or maybe he's researching his next character…