He is regarded by some as the best actor of his generation: an artist of unmatched intensity who, in collaboration with great directors, has helped create some of the finest films of the past quarter-century. But enough about Jason Priestly. I must make do with dour method-man, Robert De Niro.

We met at a posh London hotel. He came bounding into the lobby to greet me effusively - all smiles and hugs. "How wonderful to meet you, Andy!" he cried, performing a theatrical bow and hand-flourish. "Please, do come this way."

As if. This man makes hemorrhoids seem like good fun. There was no warm welcome for me, no welcome at all in fact. In true superstar style, my interviewee was late. So I sat alone for 30 minutes, scratching my bollocks for want of anything better to do. I think I might have tics or something. The receptionist wasn't happy: he kept glaring at me. Tough, I thought. If you don't like it, either say something or put up a sign - 'We kindly ask our guests not to touch, fondle or scratch their genitalia in the lobby.' On reflection, though, maybe I should have left my pants on.

Eventually, De Niro turned up, agent in tow. "You have 20 minutes, no longer," the agent grunted. "Then you go. And no questions of a personal nature. Got it?"

"Understood," I said, zipping myself up. "Mr. De Niro , is it true that you suffer from premature ejaculation on the rare occasions you manage to get it up?"

It took a while to convince them to come back, that it was a just a joke and that I was genuinely sorry for any offence caused. "This is your last life," the agent warned me. Yeah yeah.

You know this but I'll tell you anyway because I'm a bluff buff. A gifted student from the Lee Strasberg acting school in New York, Robert De Niro first came to public attention in the early 1970s with impressive performances in Scorcese's Mean Streets and Coppola's The Godfather Part II, the latter earning him an Oscar for best supporting actor. He went on to do his best work with Scorsese in Taxi Driver and Raging Bull, both films moulded around De Niro's compelling portraits of alienated fuck-ups.

Pretty much everything he's been in since then, Goodfellas excepted, has been toss. Like Heat, for instance. What a load of rubbish that was. I never saw the end because I switched it off - it bored me to tears. Ditto The Mission. And the ditto Deer Hunter, a much earlier release. Hailed as a masterpiece, this takes about three weeks to get going and the only reason the Russian roulette scenes have the impact they do is because by then the poor viewer has taken to gluing his eyes open in a bid to fight off impending slumber. None of this is De Niro's fault; I'm not saying he can't act, just that his taste appears to have gone downhill (surely this is self-evident when you see him acting opposite Robin Williams and Billy Crystal. What next: Chevy Chase?) He also seems more reliant than most on good material. Give him a poor script and an average director and he flounders; he can't carry a bad film in the way that Al Pacino, for all his descent into pantomime ham, can. A true martyr to his method roots, De Niro's on-screen charisma is commensurate with the characters he absorbs.

Right. So what of his fabled method techniques? Personally I've always been skeptical of actors 'immersing' themselves in roles. Take Daniel Day-Lewis. He locked himself in a prison cell for two weeks to 'get into the part' of Gerald Conlon, a wrongly accused terrorist who spent 14 years in prison. This smacks of half-measures: if Day-Lewis was really serious about the job he'd have locked himself up for 14 years, not 14 days. I reckon that's what Marlon Brando's doing - he's preparing himself for the role of a lifetime in which he plays an extremely rich and immensely fat man preparing for the role of a lifetime.

But what's wrong with just pretending? That is what actors are supposed to do, isn't it? I remember pretending to be a tree in school drama lessons. It was a piece of piss; I just stood with my arms at funny angles and a blank expression on my face. I made the role my own, and was made First Tree in the nativity play. A victim of my own success, I became typecast: when I asked to play Joseph in next year's play, the teacher refused. She said I was too wooden. Thus was a promising career cruelly dashed. But imagine if De Niro was playing a tree. He wouldn't just pretend. Presumably he'd hang around woods for weeks on end, standing stock-still and cultivating fungi.

"Don't be a fucking idiot," he answered. "Ask me some proper questions."

"The point I'm making is why not just pretend? I say to you, here's Travis Bickle, he's a taxi driver with a chip on his soldier, read the script then pretend to be him. You don't have to drive around in a taxi for two weeks to prepare. Everyone knows what taxi drivers do - they drive taxis."

"That's not how I was taught," De Niro replied, "and it's not how I work. What works for me is what I do."

Well you can't argue with that. But I could. "It doesn't always work. Look at Harvey Keitel in The Piano. What sort of accent in that? Not bloody Scottish, I can tell you. If that's where method-acting gets you, you can stick it up your arse."

"That's an your opinion, you're entitled to it. But Harvey's a friend of mine, whom I greatly respect, so soften your tone."

"Yeah, okay, keep your hair on. Lets move on to Raging Bull. Many regard your performance in this as your finest to date. To convince as the aging Jake La Motta, you binged on food to put on the required weight. Be honest - this was just an excuse to pig out on loads of pasta and wine, wasn't it? A few cushions would have done the trick just as well. I'm surprised you didn't audition for the role of the chocolate fiend in 'Willy Wonker and the Chocolate Factory'. You'd have liked that one. All that chocolate."

"Are you taking the piss?"

"A bit."

"Okay, this interview is terminated."

"Don't go yet, Mr. De Niro."

The agent intervened. "I'm sorry Mr. Bluff, your allotted time is up and my client is a busy man."

"Rubbish! I've only had ten minutes."

"Perhaps you should adopt a more constructive line of questioning in future. Mr. De Niro has a new film marked for imminent release. Were you to publicise this, we might be persuaded to stay a little longer."

"But I don't care about his new film."

"No. That much is evident. Goodbye then Mr. Bluff."

The two men rose and walked across the lobby to the elevators. As they stood waiting I called out to De Niro, in a voice as genuine as I could muster.

"Goodbye Mr. De Niro. It was nice to meet you."

He signaled a goodbye with his hand, kept his eyes fixed on the floor.

Then I added, louder: "You fat bastard."