JK Rowling has sparked a new genre of fiction with her mega-selling Harry Potter novels - books that appeal to children and grown-ups alike, reports STEPHEN LEWIS.

ELLA Waddington will be the envy of just about every child in York tonight.

It was her name that was pulled out of the hat in a competition run by the Evening Press and Waterstone's bookshop to find a Harry Potter VIP (Very Important Potter fan).

Her prize: first place in the Harry Potter queue at Waterstone's in York this evening and the honour of unveiling the sixth Harry book - Harry Potter And The Half-Blood Prince - when it goes on sale at one minute past midnight.

The ten-year-old from Burnholme has already got herself a fetching witch's (or should that be female wizard's?) costume and an imposing-looking wand ready for the big night. But it will be a while before she reads her free copy of the Half Blood Prince.

"I'm only on the third one The Prisoner Of Azkaban at the moment," she said, looking the very image of a youthful Hermione Granger. "I've just got to the bit where the lady Mrs Dursley starts to blow up!"

Regardless of what happened to Mrs Dursley (you'll have to read the book to find out), there is no sign that the Harry Potter bubble is about to burst. Early indications, based on pre-orders of the Half Blood Prince, are that first day sales will be on a par with the staggering 1.7m copies of Order Of The Phoenix, the last Harry Potter book, that were sold.

It may not only be children who envy Ella her VIP status. All the signs are that grown-ups are just as crazy about the Potter books as their children. Waterstone's predict 250,000 copies of the special adult edition of Half-Blood Prince will be sold in the first 24 hours - and that the book will go on to become one of the best-selling 'adult' books of all time.

Harry's phenomenal success has, in fact, sparked a new literary genre: what the book trade is calling the 'crossover' book - children's books that have 'crossed over' into the adult market.

Grown-ups across the country are re-discovering their inner child, devouring books by the likes of JK Rowling, Philip Pullman, Roald Dahl and North Yorkshire's own Graham "GP" Taylor.

Booksellers keen to cash in on the phenomenon are re-issuing many of the children's classics in adult covers designed for more sophisticated tastes. CS Lewis's Narnia books are the latest to receive this treatment. A new adult edition of the seven-book series, published by HarperCollins, appeared for the first time this month, complete with discussion points for book groups at the back.

Graham Taylor, the former Cloughton vicar whose first novel Shadowmancer became a smash hit, admits his own books are classic examples of the 'crossover' phenomenon - books which appeal to readers of all ages.

Although Shadowmancer was originally packaged as a children's book, Graham's gripping tale of magic, sorcery and wickedness set on the 18th century Yorkshire coast around Ravenscar appealed to young and old readers alike.

"In fact 60 per cent of my readers are adult," he said.

There is nothing strange about grown-up readers turning to children's fiction for their reading, Graham says. "A lot of adult fiction is just tripe. It doesn't deal with the great questions of life - what happens when we die, is there an after-life, that kind of thing. All they write about is old, bald men sleeping with pretty women. There is nothing challenging.

"The world of children's fiction is much richer - far more adventurous, descriptive, challenging and gorgeous. And often the standard of writing is a lot better. Adult fiction is often written in a newspaper style, with no description or character development."

The term 'crossover book' may be new, but actually, there's nothing new in the phenomenon itself, Graham insists. It goes back to Roald Dahl - and even further, right back to Charles Dickens. Graham sees no harm in it: in fact, he would like to see the distinction between children's and adults' books scrapped, and separate children's and adults' sections in bookshops done away with.

He had a letter recently from a reader in the United States, who had read Shadowmancer at the same time as his daughter. "And he said that for the first time they had something to share a conversation about," said Graham.

Books that appeal across the age gap can help bring the generations closer together, something any parent of a Potter fan who has read the Harry Potter books themselves will appreciate.

Jo Dodd of York's Worm Holes bookshop, in Bootham, agrees with Graham that in many ways children's fiction is richer, more varied and more imaginative than adult fiction.

"Many adults have lost the pleasure of reading," she said. "You've got the crime fiction, the thrillers, but where do you go for a good adventure that's imaginative and that takes you away from reality?"

Adult literary fiction isn't much better, she says. "A lot of adults find it hard to read some of the literary stuff. It's badly written. It doesn't have a beginning, a middle or an end."

A good children's book is often much better written than a poor adult book, Jo says - and it has the added benefit of taking us back to the world of our childhood.

Certainly it's hard to think of any adult book that could cause a fraction of the anticipation that a new Harry Potter does.

Just the other day, Jo says, she had four little boys come into her shop. "They were going 'when is it due, when is it due?' and 'do you know who is going to get killed?'" she said.

Tens of thousands of children and a fair few adults up and down the country have been wondering exactly the same thing over the last few days and weeks. Now there's the power of a good book for you.

Bookshops across York will be open at midnight tonight as the first copies of The Half-Blood Prince go on sale at one minute past. Shops staying open include Borders, Waterstones, Worm Holes, and WH Smiths at Monks Cross and Coney Street. The Little Apple Bookshop in High Petergate will be opening at 8am tomorrow.

Updated: 10:15 Friday, July 15, 2005