Sonya Hartnett, the bestselling Australian novelist who had left childhood behind well before she wrote her first novel at 13, only recently began to create fictional children. She met the boy at the centre of her new novel, What the Birds See, in a Melbourne primary school in the mid-1990s when she spent seven weeks there making props for school plays.

“This boy of about nine had a vile family,” she says. “I’d watch him go off with his horrible mother and his bullying older brother and my heart would sink.He would come to school in shorts and a grubby T-shirt in winter, and his hair was never brushed.

“He would come into the art room every day to help me. When I asked if he should be doing some other work, the teacher said he would benefit more from staying with me because I was the only adult who’d ever paid him attention.

“He didn’t say a word for the first two weeks, but he watched me like a hawk so he could help me make whatever was needed, without me asking. It was hard to say goodbye to him. I can see why teachers have to learn to switch off.”

In the book (the Australian title, About a Boy, has been changed for the UK) Adrian is neglected emotionally rather than physically, and brought up dutifully but joylessly by his grandmother.

“I’m interested in the collision of two worlds in intense relationships between grandparents and grandchildren,” Hartnett says. “Adrian’s grandmother is from the generation that don’t show their feelings.”

The story is set in 1977, when Hartnett herself turned nine. On the fringes of the novel is a famous Australian case of three missing children, Jane, Arnna and Grant Beaumont, who disappeared in 1966 near Adelaide. In Hartnett’s book, media coverage and adults’ anxiety after three local children vanish leave Adrian convinced, briefly, that the siblings have moved in next door and that their brusque father has kidnapped them.

Adrian has many troubles that Hartnett remembers from her own childhood in a lower middle-class suburb of Melbourne, where she took the same route to the milk bar (“two right turns, two left”) as the children on their final journey to buy ice cream.

She was one of six children, but spent most of her childhood alone. “I would wait by the school fence at break, and hope my mum would see me and take me home.” Escape came from riding her bike through the scrubland near her home and later through writing.

“Writing must be in my blood, although we weren’t a bookish family,” she says. “I wrote a story for homework when I was nine, and was relieved to have found something I could do.”

She pinpoints the moment when she began to place herself in the adult world. On a family holiday, she and her cousins had wrecked her uncles’

hotel room for a joke, and the police were called.“I hid under the bed until it was all over,” she recalls. “In an instant, I realised that I was a dumb ignorant kid and had no idea how the world worked; I started to see it through different eyes.

“I would never go back to being a child. That sense of powerlessness, of feeling isolated and vulnerable in a world beyond my control, has coloured a lot of my work.”

She finished her first novel, Trouble all the Way, at 13 and looked under P for publisher in the Yellow Pages.“Only a 13-year-old would take that approach. I couldn’t afford much postage, so I looked for a publisher in Melbourne.”

Her manuscript reached a small textbook publisher, Rigby.“They didn’t receive many novels, not from kids anyway, and must have decided to encourage me.”

She wrote 10 novels over the next two decades, mainly centred around characters in their early 20s and aimed at a young adults. Wilful Blue and Sleeping Dogs are the best known but are not published in the UK. Thursday’s Child, which won the Guardian Children’s Fiction Prize in 2002, has launched her in this country, but it is untypical of her work and is not a straightforward children’s book because much of it requires an adult’s understanding. Set in the Australian depression, it introduces a distressed boy called Tin, who tunnels underground as his family struggles to survive on their farm. He is inspired by some ants that Hartnett watched while gardening.

“Ants can supply everything they want for themselves but humans have long forgotten that possibility,” she says. “I wanted Tin to have our essential animal core at his centre. If I could start my life again, I’d study zoology.”

The pressures on Tin’s family mean that he can retreat to his own world without intervention by adults. “Times of extremes are good to set books in,” she says. “The rules of life become different. A kid like Tin with quite a dangerous edge could exist then.”

Her part-time job at the Melbourne primary is one of a string of day jobs that have supported her writing. She is now on the brink of giving up working in a bookshop at weekends.

“I’m never certain that I’ll be able to think of another book,” she says. “I feel secure in my talent, but not convinced that the ideas will keep coming. I started young, so I’ve already written a career’s worth of books.”

She is working on a book for young teenagers, but insists that What the Birds See is not intended for children, although it is published by Walker. The bleak ending and the emphasis on a boy who lives mostly inside himself (as her characters often do) means it is unlikely to appeal to readers under 15.

“Kids of Adrian’s age won’t think it an interesting story - they are too close to being children. It’s only as you move away from childhood that you see it clearly. There’s nothing poignant about it when you’re still in it.”

‘What the Birds See’ by Sonya Hartnett is published by Walker Books, pound;7.99