Woody Allen has been playing himself for so many years now that one wonders if his personality might, at some stage, actually run out. He admits that when he is filming he grows tired of his image and, for the past few years, audiences have tired of it too. But when asked if he worries whether he might, one day, stop being funny he says, "Well, no. Because if I wake up, I'm going to be funny, because it's me. It's not that I put on a thing to do it; I wake up in the morning and I can write. I roll out of bed and I can write; I can write - that's what I do, that's me. So it would have to be a complete personality change for that to happen."

Allen at 70 looks little different to the young man who appeared in Play It Again, Sam in 1972. His agelessness is often remarked upon and it is curious; the pale, unlined face is soft-looking, like moleskin, and the eyes are wide, in the way of all creatures who spend too much time straining to see through the dark. On the evidence of our interview, Allen's public persona is a barely exaggerated version of his private self; he really does whine; he really does see the world as a tragic place; he really is amused, in a ghoulish way, by the suspension of disbelief that allows people to function in the face of their own mortality. You either like him for this or you don't; if you do (I do), then the shtick is enough to make even in the slightest of his films a joy; if you don't, he is simply horrid.

Even so, for the past decade, ever since the triumph of Bullets Over Broadway (it was nominated for eight Oscars and won one), Woody Allen films have been a little samey, have looked a little tired, which is why his new production, Match Point, benefits greatly from the fact that he is not in it. It is the first film he has shot in London and it is big and long and serious, something the audience is tipped off about early on when the lead character, played by Jonathan Rhys-Meyers, is filmed casually reading Crime and Punishment (Allen says the book "puts my movie to shame"). Although the title sounds like a made-for-TV movie, this is Allen as the sort of film-maker he has always admired, but rather defensively sent up. It tackles big, Greek themes, with a classical score, beautifully shot and shockingly concluded. The film revisits the age-old debate of character versus fate, faith versus self-determination and above all, luck; at what stage does a series of bad line calls constitute a destiny?

"I had an idea about wanting to do something about the role that luck plays in life," he says, "and that we're all terrified to face up to that. Everyone wants to think that they, you know, control their lives, or at least have some control. You like to think, you know, well, if I exercise and eat right and don't smoke, I'm going to ... But that doesn't do it. And no amount of planning can account for the big part that luck plays. I wanted to write a story that would illustrate that."

Is he lucky? Yes, he says; he must be, in some way, merely by virtue of the fact that he is successful.

"People are often not honest about it, but the truth of the matter is that you are very dependent on ... You know, when I started in show business, there were guys and girls who were as talented as me or more; and you know, one died in a plane crash. You know ... what can you ... you need luck. It's a very, very important part of your life, and you don't acknowledge that."

Match Point is still very obviously a Woody Allen production; the incidental chat, although it is strange to hear it being spoken in London rather than New York vernacular, is sharp and funny and, he says, improvised as usual, by a supporting cast that includes Penelope Wilton and Brian Cox. The film suffers slightly from an American director's tourist-board view of London - the characters are forever hanging around outside Tate Modern, or Buckingham Palace as the changing of the guard is going on. But it is otherwise an assured portrait of the upper middle classes and what happens when people stop feeling accountable for their actions. "I anglicised it myself but I asked an [English] friend to go over it and point out where I made blunders. Occasionally an actor would say, 'You'd really say "dodgy" and not "dicey" here', or something."

Allen does not read his own reviews, or rewatch his own films, once they are finished. The former do not mean anything to him - "If the reviews were good, it never changed my life for the better; and if the reviews were bad, it never changed my life for the worse" - and the latter, well, he is more often than not unhappy with a film once he has finished it, and watching it again just brings down his mood. He envies easier personality types, those of his peers who can finish a film and go to a big party on opening night and at least give a good impression of enjoying themselves. But Allen does not get pleasure from it. "I just work from film to film and I'm almost burning on a low flame of depression. You know? It's not the kind of depression that sends you to use drugs or medicine. But, you know, I don't really care if people don't like a film of mine very much, and I don't really get much pleasure if the film is successful." This sounds to me like an extraordinary self-confidence. He laughs.

"It's a kind of, um, it's an apathy that's mistaken for either reclusiveness or arrogance or could be mistaken for confidence. But it's not."

His neuroses are, of course, what made him; the funny little guy who always won the beautiful girl, be she Diane Keaton or Mira Sorvino or Julia Roberts or, more recently, Charlize Theron. He cast Scarlett Johansson in Match Point, and she is very good, but Allen has never disguised the buzz he gets from surrounding himself with beautiful women, or failed to point out that he would not get within 10 feet of them if he wasn't a successful film-maker. "He's a sleazy little megalomaniac who's frightened of women," said Helen Hunt's character in the Curse of the Jade Scorpion, and this is Allen turning directly to his critics and saying, I know, I know - but can you blame me?

I wonder if he would at any time have traded being funny for being beautiful himself? "Not beautiful, 'cos I've never cared about that. But I would've exchanged being funny for being a tragedian. Yuh. I always would've done that, from day one, to now, I mean, I always would have preferred that. Not as a performer: I'm not one of those people that wants to play Hamlet; I couldn't care less about that. But I wish my career could have been one in which film after film had not been comedies, but been dramas and tragedies."

Because they are taken more seriously?

"Because I take them more seriously."

This is a discussion that Allen started in his film before last, Melinda and Melinda, and which Match Point continues: whether life is essentially comic or tragic. The conceit in Melinda was a bit laboured and the film not well received - in it, Allen filmed two parallel interpretations of a single story, each illustrating either a comic or a tragic possibility. I assume he comes down on the side of life being tragic?

"Oh, clearly. Without any question I think life is tragic. There are oases of comedy within it. But, when the day is done and it's all over, the news is bad. We come to an unpleasant end."

The death of Allen's own parents was, he says, a relatively "minor" event; his father was "slightly over 100"; his mother was "95, and, you know, it had no resonance, or trauma. These were elderly people who had led long, good lives, and were in decline in their last years." This isn't to say that he has reached an accommodation with himself over the prospect of dying. "No, I haven't. And getting older has no redeeming quality. I haven't mellowed, I haven't gained any wisdom, it's a bad thing. You don't wanna get older, it has nothing going for it."

Isn't having children a consolation of some sort? Allen has two adopted and one biological child with Mia Farrow, and has adopted two more with Soon-Yi, Farrow's adopted daughter with André Previn, whom he married in 1997. "No. There's no sense of continuity. No sense of, no sense of ... I always used to think that art is the intellectual's Catholicism. You think that because your work may by seen after your death, or read, after your death, that it's compensation. But it's not. Not kids, or art or anything. There is nothing compensating about your own death."

He has not mellowed because he says he was never "unmellow"; not, for example, like Groucho Marx, "who was a terror. But I was never a terror."

When he married Soon-Yi, however, that is how he was portrayed in the press. During the bitter custody battle he fought with Farrow she accused him of abusing one of the children, for which no evidence was found. He says he kept his head down throughout the court case and survived the media onslaught because of this "low-flame depression" which he always runs on. "The legal part of it, my lawyers handled. And I stayed home and worked, while everything was going on. I did Manhattan Murder Mystery; I did the jazz documentary, I did Bullets Over Broadway, I did Death Defying Acts, a play. It was not the kind of thing that was on my mind, believe it or not, because there was nothing I could do about it, it was strictly a legal thing. Much of what I heard about it was way off the mark; I don't mean wrong in a derogatory way to me, just not even close to what was going on. And so it was fine."

His marriage to Soon-Yi continues to surprise him. If anyone had told him he would find stability and happiness with, as he puts it, "an Asian woman, not in showbusiness, much younger than me, I would have thought they were crazy. 'Cos all the women I went out with were in showbusiness, they were my age, they were little blonde girls, you know. But this has been just great, totally."

Is she relaxed about him working with lots of beautiful women?

"She's reasonably cool with it. I mean, I think she would feel 100% comfortable if I was working with, you know, Robin Williams. But she's generally OK with it, and I'm no threat, so it's OK."

I ask if he still has contact with his other children.

"Uh-uh."

No?

"No. I don't have contact." He says he has agreed not to publicly discuss it. Does Soon-Yi ever see Mia Farrow these days? Allen looks horrified.

"Oh no, no. God no."

There was a time when this conversation with Allen would have blotted out all others; when his public persona as a harmless geek who, if he caused pain, at least suffered commensurately himself, was replaced by that of a sleaze and a predator; when even his most ardent fans found him distasteful and picked over his back catalogue for signs that he was always like that. Those days seem now to have passed; those who said they could never watch a Woody Allen film in the same way again have, in the way of these things, mostly forgotten. In any case, there haven't been many must-see Allen films in the past 10 years. Match Point is his return to form - more than that, perhaps; at 70, the beginning of a new maturity.

None of this changes anything in his own mind. The day before I see Allen he has finished making another film, called Scoop, also shot in London and starring Scarlett Johansson, to be released next year. How does he feel about it?

"Very negative," he says, and his eyes open wide.