Jacqueline Wilson will be in York on Friday to sign copies of her new book Best Friends.

STEPHEN LEWIS asks the author about her enduring appeal to young readers.

JACQUELINE Wilson corrects me gently when I suggest she's Britain's top-selling author. "I'm the most borrowed author in libraries," she says, in a slightly Miss Marpleish tone.

It is an accolade nevertheless - and with more than 12 million copies of her books sold in the UK alone, she's hardly doing badly in the sales stakes either.

Her popularity is obvious whenever she turns up at a book shop for a signing. Queues wind round the block, mums and dads holding the hand of excited little girls desperate to meet their favourite author. At one recent signing in Bournemouth, where 3,000 people reportedly turned up, she didn't get away until after midnight.

"It's ridiculous!" Jacqueline says, sounding chuffed. "It's wonderful for me, but it must be exhausting for the parents standing there with their little girls. But it seems to be something they are willing to do."

No doubt there will be queues round the block when she arrives at Waterstone's in York on Friday to sign copies of her latest book, Best Friends.

Reading the book, it is obvious why she is so popular, especially among girls.

The plot is simple. Alice and Gemma have been best friends since they were born. They went to nursery together; they went to infants' school together; now they are in the juniors together and are still best friends.

It doesn't matter that Alice is neat and tidy and likes trying on nail varnish and jewellery whereas Gemma is loud, boisterous, loves football and longs for a tree house in the garden. They are inseparable and tell each other everything.

Then Alice's snobbish parents decide they are going to move to Scotland, and the two little girls' world falls apart. How can they stay best friends for ever and ever when they're so far apart?

The book effortlessly captures the anguish and helplessness of the two girls as their parents decide their lives for them. It's written from the point of view of boisterous, bolshie Gemma; who when she learns Alice's parents are taking her away to Scotland, lets fly at Alice's mum Karen:

"'It's all your fault!' I shouted. Auntie Karen jumped. Alice gasped. Mum shot up and seized me by the shoulders.

"'Be quiet, Gemma!'

"'I won't be quiet!' I roared. 'It's not fair. I hate you, Auntie Karen. You're taking my best ever friend away from me and you don't even care!'"

What's remarkable is the effortless, seemingly artless way the best-selling author is able to put herself into the hearts and minds of the little girls she's writing for, and write as though she's one of them. How does she do it?

Partly by remembering her own daughter (long since grown up), she says. But partly it is remembering her childhood.

"I seem to have total recall of my own childhood. I just imagine myself inside the head of a child and write as if I am one. As a middle-aged woman you'd think I would find it difficult, but I just seem able to do it."

It certainly seems to have worked with Best Friends. The book has only been out a couple of weeks, but already Jacqueline has received letters from girls saying it is just how they feel. Girls in particular do have best friends, she says - and if they are forced apart they can be inconsolable.

"As adults, we don't take it too seriously. But for the children themselves it can be very difficult to cope with."

The other reason her books are popular is that they are easy to read - and great fun. Gemma in particular was huge fun to write, Jacqueline says. "She's rather a tomboy. Well meaning, but the sort of child that if you hear a crash from the kitchen you know exactly who has done it!"

Fans of Jacqueline Wilson will also be delighted at the return of one of her favourite characters - Biscuits. He's the class fat boy, but unlike too many overweight children in books, he's proud of it. It's impossible to imagine anyone picking on Biscuits, despite his fondness for chocolate cream cakes, because he's so full of life and irrepressible energy.

"I love it that children do find him a fun character and like him," says Jacqueline. "I cannot stand those books where there is a fat boy or fat girl and they go on a diet. Children need to feel fine in themselves."

Biscuits certainly does: and he proves himself to be a friend indeed to Gemma once Alice goes to Scotland. Not her best friend forever - that will always be Alice - but her best mate. It is a great way to end what is a heart-warming story from a master storyteller.

Best Friends is published by Random House children's books, price £10.99. Jacqueline Wilson will be at Waterstones in Ousegate, York, at 4pm on Friday to sign copies of the book. Waterstones staff say to expect queues of up to five hours - so it may be worth turning up a little earlier if you can.

Updated: 08:50 Wednesday, March 17, 2004