When I arrived, Curtis was pacing up and down at the thought of having to do an interview, and things did not get off to a good start. He refused to answer the not terribly probing question, "Are you thrilled about the Oscar nomination?" on the grounds it was too personal. It took time for the charming, generous and good-natured man that he is to emerge.
He distrusts the press, he says, because 15 years ago the Daily Express said, wrongly, that he disliked his old school, Harrow (he quickly wrote to Harrow to put that right). In addition, a few years ago he was misquoted as saying something snide about Emma Thompson, who in fact is a good friend. These were not, on the face of it, the most blatant examples of the press drinking in the last chance saloon. But they give an insight into how protective Curtis is about his personal life.
Perhaps he sees me as a soft touch. After all, I stifle the congratulations to him and his girlfriend Emma Freud on the forthcoming happy event, completely failed to understand Angus Deayton's joke at the Comic Relief launch that Curtis's next film will be called No Weddings and a Baby, and if there are former girlfriends of Curtis who claim to recognise chunks of the man in the Hugh Grant character in Four Weddings, I fail to mention them. Not that Curtis would have consented to such an interview. We are here to discuss Comic Relief, a passion that Curtis is prepared to share, even if his uneasiness about breaking the habit of his adult lifetime means he unconsciously tears a plastic teaspoon into a dozen pieces as he does so.
Curtis started Comic Relief with his friend Jane Tewson in 1985, when they both went out to Africa for Oxfam and Save the Children. Having already scripted Blackadder and Not the Nine O'Clock News, he knew enough comedians to talk to and discuss how to proceed further. The first initiative was to bring Cliff Richard and the Young Ones together for the single "Living Doll", and then do a live stage show at the Shaftesbury Theatre.
"But then Lenny, Dawn and I were talking one evening, and I thought, there's something slightly doolally - all these comedians make their living entirely out of television, but when they do something for charity they do it on stage."
The rest is television history and millions of pounds raised for charity. This year Curtis wants to make the show more unusual, and his own contribution to Comic Relief Day on 17 March will be the the sequel to Oliver Twist - Oliver, the Final Twist, a series of sketches (starring Dame Diana Rigg, Jeremy Irons, and Oliver originals Ron Moody and Oliver Reed), which began life as a film script but was abandoned when Curtis realised that not even the 17 revisions he made for Four Weddings would make it work as a feature.
Curtis is using his influence to encourage the artists "to do something special, something they wouldn't do in any other circumstances". Irons is playing a 3ft-high insane villain; Victoria Wood and Dawn French will be working together for the first time on a double act, and Rowan Atkinson will be skating with Jane Torvill for Torvill and Bean.
Given his reticence, it is perhaps not surprising that Curtis will not be appearing himself. But Curtis is no slouch under the spotlight. He has a photogenic, open face under a Harpo Marxesque shock of golden curls, and showed, when he received the Evening Standard Film Award for Four Weddings, that he could bring the house down with his dry humour. After Stephen Fry had paid him a few gratuitous insults, Curtis revealed that one of the characters in Four Weddings was modelled on Fry, but, he added, "I never felt that Andie McDowell really caught the essence of the man."
Curtis, though, recalls that he has appeared professionally on stage, in the West End, no less, for a revue with Rowan Atkinson. He will never do so again. "I was completely invisible. I once went on stage with a bleeding nose and Rowan said you can't, but I said, just you wait, no one will notice. And no one did. But then again, I never wrote myself very good lines."
Curtis, who is 37, started writing comedy sketches with Atkinson at Oxford and has kept up the association in Not the Nine O'Clock News, Blackadder and Mr Bean. He looks back on the writing of Blackadder with Ben Elton as one of his happiest experiences. "I've always thought the ideal job must be that of a lyricist. You write some words and the composer gives them back to you in this ideal form which transforms your words into another dimension. With Ben I would get this ideal form."
Perhaps his most surprising outing, though, has been The Vicar of Dibley, a hugely popular but curiously old- fashioned sitcom, given the surreal excesses of Bean and Blackadder. Dawn French, its star, puts the change of gear down to the fact that Curtis "has tried to write something about goodness, which is a supposedly naff thing to do, but he finds it sad that the Eighties have taught us to be sneering; he thinks it might be time to change things."
Curtis, typically, argues only with the one word that has a derogatory overtone. "I don't think I would have said sneering. I was part of a tradition, one which still gloriously thrives in Absolutely Fabulous, of people who behave badly and are aggressive, and in Dawn's view I was trying to start something different... After doing four series of Blackadder and having Blackadder be rude about Baldrick five times a week, it was nice to write a sitcom about someone who was nice to Baldrick five times a week. The relationship between Dawn and Emma Chambers is a benign version of Blackadder and Baldrick."
Once the Comic Relief fund-raising is over, he will head for Hollywood and the Oscar ceremonies, where Four Weddings is up against Tarantino's Pulp Fiction, which pipped him for the Golden Globes. Curtis talks enthusiastically about Tarantino's movie, saying, surprisingly, that he thought it similar to Four Weddings. "It was funny and you got to know each character for a while and then moved on, which is what I tried to do. I wouldn't see Reservoir Dogs because I hate violence. But Pulp Fiction was different. John Travolta doesn't really die because he comes back."
It's taken an hour of stops and starts, but Richard Curtis is now chatting animatedly and entertainingly. I chance my arm again with that deeply personal question of whether he is thrilled by the Oscar nomination.
"Oh, look, of course I'm delighted. But I feel it's like one of those bullfighting posters, do you remember?, which has your name on in the middle of all the real stars. This fax comes from Hollywood, and it lists Paul Newman and Tom Hanks and me, and you think it must be a mistake. But either way I can't lose. If I don't win I don't have to make a speech. It is terrifying to think of having to make a speech."
And his antipathy to interviews? "It's over-sensitivity, I suppose. You have delicate working relationships with people. I wouldn't want the people involved in Comic Relief to think I'm trying to take any credit because the credit is theirs. And then there are the inaccuracies. When I read that snide remark about Emma Thompson I got depressed for days afterwards."