Joseph Heller in conversation with Mark Lawson

Chelsfield Room, South Bank Centre.

"Anybody in the back?" Joseph Heller (right) bawls out all of a sudden, sick of taking questions from the front rows. His voice is raw and growly, like a Coney Island ice-cream vendor's. He is an old man now with snowy- white hair, plump as a capon, and his genial demeanour is that of a man who has lived high on the hog, and long basked in the steady sunlight of self-approval. Hell's bells, why not, though? Who else wrote Catch- 22? What other novel has been in print continuously for nigh on 40 years?

Heller's in England this week to promote his autobiography, a kind of enthusiasts' addendum to the fiction. He tells prospective purchasers of the book to expect nothing more than a signature. If they want something longer, they should linger at the back until the crowds disperse.

Mark Lawson, a journalist, treats him reverentially, as if he's a piece of family Wedgwood, bowing low over his notepad scribblings, twisting his head sideways as he speaks. The two men never seem to be on a level with each other. Which is exactly as it should be, of course.

Isn't the way that he writes his novels quite unique? Lawson prompts. Heller guffaws at that. Of course it is - like much else about him. The novels never begin with plans or carefully worked-out notions of where the thing may be going - nothing so simple or unoriginal as that. Every one of them has begun with a sentence - or maybe even a batch of sentences - leaping into his head, demanding to be written down before it disappears as mysteriously as it came. Of course, many of those sentences didn't turn into anything at all.

One or two of these he throws out to the audience - for quick kids to make novels of their own out of, if they possess the daring, the persistence, the skill. What about the sex novel written for women that begins with a steal from the Duke of Marlborough's diary, for example? "Last night my lord came home and pleasured me with his boots on." Or that first shot at a second biblical epic: "The Lord, they say, was born in a manger, but frankly I have my doubts."

This is the way Heller works, then: he sits back in the sun and waits for a sentence. And when that sentence has turned up, he chips away at the thing, working in long-hand at first, maybe 300 words a day, three pages of the pad, for year after year if necessary - the follow-up to Catch-22 took 13 years, but they've been coming faster since. More prosperity has meant more writing time. He has no regrets, none whatsoever, that he's written only eight books to Updike's 57. Frankly, he tells us, "I don't know what books I'd have written had I had more time. Ideas come one at a time ..."

And, yes, generally speaking, he had a good time as a bombardier in the war - in spite of what Yossarian may have intimated. And anyway, even Yossarian aged and mellowed in Closing Time, the sequel to Catch-22. He may have won the war against Hitler, but he lost the war of independence by taking a job. Heller smiles knowingly, and quotes himself: "If we're not careful, we grow up into the kind of people we used to despise."