The childless Quentin Blake's wry and cunning lines have secured him a place in young readers' affections. Sally Williams meets an artist who draws as he breathes
People say such nice things about Quentin Blake. That his scratchy style is alive and electric. That he makes it look so easy. That he fills the page in the most exciting way, can really draw and says so much just with a line. That he knows exactly the right moment to illustrate, and even hints at things that aren't there. That his own books are funny, sad and full of eccentric characters, that Simpkin and Mister Magnolia especially are great to read aloud again and again. And that at the Royal College of Art he was a fabulous teacher, the whole reason that fellow- illustrator Emma Chichester Clark decided to study there.

So, has anybody ever said anything bad about Quentin Blake? "There was a parent once," he says, gazing out of the large window of his bright, high-ceilinged Earl's Court flat, "who said he thought I was selling children short." Even he, concedes Blake, had to add: "But they seem to like it."

At 65, small, elfin, balding with grey hair sticking out at a dozen angles, Blake looks as if he has just stepped out from one of his books. He is untidily dressed in canvas plimsolls, baggy trousers, ratty old track- suit (a rig, say friends, he wears at home and at smart parties in New York). He radiates joviality - his eyes peep out from corrugated laugh lines - and is utterly beguiling. His manner, however, is more considered ("a friend said I have a certain slothful energy") than his high-spirited drawings would suggest. He is upset by nosy enquiries and falls into silences of the most squirming kind. He is diffident, yes. But behind that you can detect a lot of clear-headed professionalism.

He does seem genuinely astonished by the fact that he is one of the illustrators children can name. "I got 500 mentions or something in a Roehampton Institute survey," he says waving his arms around vaguely. "Second was Janet Ahlberg who got 50." Then there is his OBE, awarded in 1998 for "I don't know. Nobody ever told me," he laughs. "Very surprising, indeed." It isn't really.

It's been more than 35 years and 200 titles since Blake's first book for children was published: A Drink of Water, written by his friend John Yeoman, with whose gentle fun and wit he is particularly in tune. There are other collaborations: Roald Dahl, of course; but also Michael Rosen, Joan Aitken and Russell Hoban; 15 or so picture books on his own; grown- up work commissioned by the Folio Society (his most recent is a truly horrible Quasimodo for The Hunchback of Notre Dame), as well as work for his French publishers (Blake has a house in south-west France) and the odd perky pamphlet such as "Zapp! how not to electrocute yourself", commissioned by Eastern Electricity. All this plus teaching illustration at the Royal College of Art from the mid-Sixties (he was departmental head from 1978 to 1988).

It's a staggering output. How does he do it? "I said in a recent interview that I was diligent," he replies, "but actually I'm not at all," he laughs mischievously. "Diligence suggests something grim, but I do it because it's what I love doing best of all. It's like being offered delicious things to eat."

So Blake draws, all the time. As a boy Quentin was "silent, but drew a lot". While at school he was sending cartoons off to Punch and had two accepted when he was just 16. In fact, he has a real problem with not drawing. Holidays are especially difficult. He gets panicky and "can't wait to get back to his paper, nibs and ink". He's normally in his studio (in his flat) by 9.30, warms up by slicing paper with his guillotine, then starts to draw, standing at a light box with his back to the window.

"I never draw from life," he says. Neither did Honore Daumier, one of Blake's heroes. "You can either draw someone carrying a suitcase from life or from sketchbooks, or, like me, you can imagine what it feels like... It's like acting and I get to play all the parts."

Blake is not married. And, perhaps surprisingly for someone who seems to understand so well what the young like, he has no children. "You don't have to have murdered someone to play Macbeth well," he points out. As for not having children, perhaps (he says) he was too busy, and that anyway he's not the right person to have them with. He has no regrets. Some say that if he did have children, it wouldn't work anyway. He sees like a child, not a parent.

So are the irritating and uptight Professor Dupont (from Cockatoos) or the energetic and eccentric Mrs Armitage based on people he knew as a child? "No," he laughs. "Nobody as interesting as that lived in Sidcup." Blake's father had no special education, came from the North and was a civil servant; his mother was a housewife. He has one brother, 10 years older. Both parents were "sensitive" but neither was interested in books or art. It was school, a local grammar, which encouraged the young Quentin to apply to Cambridge University. He studied English at Downing, trained as a teacher, and although he decided to become an illustrator (working on Punch and the Spectator) he still loves reading. When not drawing, he is reading (in a deep squashy leather chair near the light box). Lots of his characters and stories come not from his childhood, but from books: the Dickensian Mister Magnolia and, now, the Secret Garden wilderness in The Green Ship (Cape).

Blake is the supreme collaborator for writers because he is so literary. Words really excite him. "The main collaboration is not with the author," he says, "but the text." Writers can count on Blake never to run away with their stories or try to upstage them. Unlike some. "Roald could be difficult," admits Blake. Did they row? "I tend to internalise a lot. Anyway he knew that I wanted it to be the way he wanted it to be." Were they friends? "We were very different." Dahl was tall. Blake is short. Dahl was Norwegian and dour; Blake smiley. Dahl liked motor cars and golf and snooker. Blake doesn't. "I knew him for 15 years, but the first three or four didn't count. I felt I would have got to know him yet better."

Some of Blake's finest work is in his own books. The wordless Clown (winner of the 1996 Ragazzi Prize), in particular, is extraordinarily clever and powerful. Why hasn't he done more? "Finding good ideas is very hard," he replies. But now that he's retired from the Royal College, he has more time and has recently come up with one or two rather good ones. In the meantime, he is busy, busy with commissions. He shows me a blank A5 page. It's for a Dyslexic A-Z. He's been asked to illustrate Q. Any ideas? "Well, Quasimodo. I think he might go in."

Suddenly he goes all trance-like. "There could be a quartet," he goes on softly, "... and a rather nice Queen ... yes", he whispers. "Yes ... that's right ... then, a quetzal ... what's that?", he asks himself, "a Mexican bird ... yes, a quetzal ... and perhaps then ... a quail quailing." He looks up. "That might do it." The picture is finished before he's even started.