HOW DO YOU become a bestselling children's author? For writers for older children, the answer seems to be to start as a teacher; but for Julia Donaldson, author of The Gruffalo, the answer seems to be to act and sing. Studying drama and French at Bristol University, she used to busk around Paris and Italy with her boyfriend, Malcolm. It was these songs that grew into the foundations of a career that, at 60, has made her the queen of the modern picture book.

“I would write these Flanders-and-Swann-type songs that we would sing at student balls and conventions for dental assistants,” she says, “and when Malcolm and I got married I wrote a mini-opera for our wedding. I thought of myself as a singer-songwriter, not a writer.” The busking led to a career in writing songs for children's television programmes such as Play School, but it was not until a publisher found that she couldn't get the song A Squash and a Squeeze out of her head that Donaldson's first book was commissioned in 1993. It was not an overnight success, however. She had six or seven books rejected and was so fed up with waiting for a response to The Gruffalo that, after a year's wait, she sent the text to Axel Scheffler, the German illustrator whom she had already worked with on A Squash and a Squeeze.

“I was a bit worried that The Gruffalo was too weird, but Axel read it and showed it to his editor at Macmillan,” she says. “Things are a bit changed now, but in those days, picture books had become almost like medicine with which anxious parents could dose their children. Whereas I believe that if children are having a tough time what they need is the stuff you get in ancient myths and classics.”

The Gruffalo is based on an old Eastern tale about a child and a tiger, and was “embroidered” by Donaldson into a story about how a hungry mouse, threatened by predators in a dark wood, outwits them by tricking them into believing that he's going to meet a Gruffalo. When the Gruffalo really turns up, the mouse tricks it in turn by pretending to be even more dangerous. Utterly satisfying, both for its rollocking rhyming couplets, its brilliantly clear pictures and its robust hero, it has sold more than 3.5 million copies and been translated into 40 languages. Now, after seven more books together, the incomparable Donaldson-Scheffler team is back for another outing with Stick Man.

Once again we have a lost and misunderstood hero whom a variety of other characters wish to use for their own purposes. He is retrieved by a dog, thrown into a river in a game of Pooh-sticks, woven into a swan's nest, and set on fire. But he, too, triumphs and gets back to safety in “the family tree” with a bit of help from Santa. It's a touching tale, more fearful and melancholy than the rumbustious Gruffalo, and perhaps reflects some of the sadness in Donaldson's recent life that became public when she spoke up on behalf of the charity Artlink Central, whose work in getting individuals and communities to change their lives through art is something that her late son Hamish would have particularly enjoyed.

“He inspired a number of my books, including the Princess Mirror-Belle series, and he and his friend used to play a game called stick man. He didn't need toys, he had so much imagination,” she says. “He would have so benefited from the kind of work Artlink Central does.” Hamish's untimely death was caused by the kind of mood disorder familiar in creative children. In fact, much of Donaldson's work on stage and page is loved by children of 4+ because she understands how most of them feel got at by bigger, bossier people who want to make them like themselves. The vegetarian Tyrannosaurus Drip, the Snail who travels on the Whale and the perennially late, inventive Tiddler all share the oddity and resourcefulness of fairytale heroes, asking children: Where do you fit in?

Julia Donaldson now lives in Scotland, but she and her sister grew up in a big Victorian house in Hampstead. “We had the ground floor because my father had polio,” she says. “He worked as a genetic specialist in twin studies at the Maudsley Hospital.” It was a close family in every way, with her aunt, uncle and grandmother living on the floors above. Her mother, a linguist and translator, would help her father to put on shows about the musical history of Hampstead, and from this she thinks came her love of poetry, music and drama.

“I'd like to see myself as part of the chain going back to Edward Lear, Lewis Carroll and Hilaire Belloc,” she says. She begins with an idea that she writes down in doggerel form, then crafts into verse over a period of two week of intense, hard work. Often a tune comes into her head as part of the process. Her house in Glasgow has a room devoted to theatrical props, because each of her picture books is also a stage show; and perhaps one reason why the books are such a success is that they get tried and tested in front of children - initially Donaldson's own, but now audiences such as those at Cheltenham next week. Her husband, a paediatric consultant in Glasgow, still acts in them, to the amazement of some of his patients.

“He gets all the juicy parts to play, like the Gruffalo; I'm just the mouse,” she says, with a very mouse-like touch of innocent, round-eyed mischief.

Stick Man by Julia Donaldson and Axel Scheffler
Alison Green, £10.99 Buy the book

The Times Cheltenham Literature Festival: Julia Donaldson will be acting her stories with help of her husband: October 11, noon
cheltenhamfestivals.com

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