Jacqueline Wilson: 'Why does a girl in my book snog a teacher? Because that is what girls fantasise about'

She is the UK's most-borrowed author, but can still shock

What makes Wilson so irresistible to (mostly) girls? Perhaps it's the grittiness of her subject matter. She's written about manic-depressive mothers (The Illustrated Mum), dead best friends (Vicky Angel) and homelessness (Dustbin Baby). Her new book, Love Lessons, is a deliberate attempt to break taboos.

"I was on a radio programme, and the interviewer asked me if there was any subject that I felt that nowadays you really couldn't write about in a children's book. It was live, and I said - off the top of my head - a teacher/pupil affair. I think there had recently been a court case about some silly teacher getting involved with a young teenager. I said it's such a worrying subject that I really don't see how one could write about it."

But she has. Her publisher was listening and took it as a challenge. The result is a book in which a 14-year-old pupil harbours a crush on her married art teacher - and finds it reciprocated. She even enjoys several passionate kisses with him. Snog scandal! "I did wonder, should I do this [the kiss], but then I thought, well, let's go for it. This is what many girls fantasise about, after all."

Here, Wilson has betrayed her killer instinct: she knows what girls want to read about. And she gives it to them. She's 59 years old, lives in Kingston, is separated from her husband (a policeman, who left her after 32 years of marriage) and has a grown-up daughter, Emma (a lecturer at Cambridge). But somehow she is able to think and feel like a tweenie. She's not interested in pleasing parents. She takes her role as Children's Laureate seriously (she inherited the title from Michael Morpurgo in May) and, as such, she's a responsible ambassador for children's fiction. But when she writes: "I leave it all behind. I don't write as a laureate. I write what I need to write."

Wilson is certainly not writing to please teachers. In her new book, the fictional Wentworth Comprehensive gets a fair drubbing. At points, it reads like a satire on modern teaching. Backward pupils and newly arrived refugees are shut in a Portakabin called a "Success Maker". Questions on an exam paper are fatuous (of a Shakespeare passage, it asks: "Do you think this scene was written recently? Give reasons for your answer"). Could it be that Wilson is concerned about the state of our schools?

She concedes that some schools she has visited have shocked and worried her. "In one school a child threw - not at me - a milk bottle, which nearly knocked me out. They had to call the police. They said they had to call the police in two or three times a week. That really did bother me.

"It's very difficult to relax and learn in those kinds of situations. In some schools, I think, respect from the pupils to the teachers and vice versa is gone." The remedy, she thinks "is not smaller classes, or more resources. It's staff, and their attitude. But," she laughs gently, "who am I to say, breezing in as a writer?"

In her writing, she grapples with real issues and real schools. Her mothers are on benefits, her daughters get called "slag" in the playground. She has been called "the Mike Leigh of children's fiction". ("Oh, have I?" she says, disarmingly. "I quite like that. In terms of the atmosphere, the lower-middle-class homes, yes, we're not dissimilar.") Does she think fantasy books aren't much help to kids nowadays? There's a line in Love Lessons that suggests as much: "I'd skied through all the Chalet School books ... I'd attended St Clare's with the twins, I'd been to Hogwarts with Harry. But these were old-fashioned schools, figments of the imagination." Does she ever feel that fantasy kids' books such as Harry Potter are, well, a bit of a cop-out?

Wilson makes a strangled miaow. "I think there's a place for all sorts of books," she responds, eventually. That's the kind of diplomacy that has won her the laureateship.

Wilson has a witchy appearance. She always wears black; her fingers bristle with huge, gothicky rings. But from her benign manner it's clear she's a white witch. Her hotline into children's hearts comes, perhaps, at a cost. She's unworldly - she writes in longhand, and can't catch up with Grange Hill because she can't tune her television in - and she has a thing for toys. Her latest acquisition is a rabbit dressed as a bumblebee, she tells me. "I have recently moved and - fey as it sounds - it was very difficult packing my toys into boxes, putting these sad little faces with glassy eyes away into the dark ... They're now stored in the cellar. If I were completely bonkers, I would imagine all the whimpers and bleatings coming up from them." Then, as if recollecting herself, the best-selling author suddenly pronounces: "I swear to you, I don't play with my toys!"

A LIFE IN WORDS

The Children's Laureate was born Jacqueline Aitken in 1945 in Bath, and grew up in Kingston upon Thames.

At 17, she got her first job, on a girls' magazine published in Dundee. The magazine, Jackie, was named after her.

She married William Wilson at 19, and her daughter, Emma, was born when she was 21. At 24 she published an adult crime novel; her career took off in 1982, though, when she started writing for children. In 1992 she produced her first big hit: The Story of Tracy Beaker, about a feisty girl in a children's home.

Aged 40, she decided to sit an English A-level (she got an A). Her many literary prizes include the Smarties Prize and the Children's Book Award. She was awarded an OBE in 2002. Made Children's Laureate this year, she has written more than 90 books and has sold more than 20 million copies.