One of the many Harry Potter PR yarns doing the rounds is the one about how "Hollywood" wanted to Americanise the boy-wizard, put him in a junior high school, maybe have him join forces with Buffy or God-knows-what - and how only J.K. Rowling's integrity saved Harry for Britain.

Maybe. Me, I give Hollywood more credit. Harry Potter and the Philosopher's Stone looks from here exactly like the "Special Relationship" on the big screen, in which Britain provides the posh Olde Englande Heritage (where Merlin the magician and Charles Dickens conveniently co-habit the same landscape) and America provides the bucks for the big sell.

Rowling's integrity, in other words, was pushing at an open door. Hollywood not only breezily employed half the top actors in Britain; it not only honoured the peculiar West Country tones of her loveable giant Hagrid; it even magicked up a series of Traditional Irish Jokes at the expense of Harry's classmate Seamus - jokes that weren't even in the book, bless 'em!

The movie also clearly recognises a crucial point beyond America's love of "Heritage": Harry Potter is, for many parents, a figure of reverence - he's The Boy Who Saved Reading.

Harry Potter and the Philosopher's Stone - the movie - opens by taking liberties with Rowling in order to allude to Harry as Saviour. The baby Harry is attended on a starry night by three magical figures; one of them arrives carrying him on a flying bicycle - an indirect reference to Christ via Spielberg's version of the Redeemer, E.T.

The liberties taken by director Chris Columbus more or less stop there, but the reverence lingers on. This adaptation is high-fidelity, verging on high-sterility. Harry Potter and the Philosopher's Stone only seems to remember that it's a movie when it's got some whopping great special effects to dish up; that's pretty often, to be sure, but in between times it rarely delivers the dialogue, the energy or the narrative conviction to be more than eye-candy. There's a sense that its message is: you've read the book - now see the movie so you can re-read the book.

With books as popular as these, that's someone's idea of a safe bet. Harry Potter, after all, is going to be a franchise along the lines of fellow-omnipotent-Brit James Bond, and, for want of a better cinematic formula, sticking-to-the-book is a good strategy. (Although of course the Bond films thrived by grabbing the titles and a couple of characters' names from Ian Fleming's novels and ignoring the rest in favour of their own movie template.)

Warner Bros' reverence for Holy Harry is reserved for the screen. Out in the marketplace it's an entirely different story: from the expensive mail-order Harry Potter jewellery to the Harry Potter sweets in the corner shop, few boundaries of commerce have been acknowledged, much to the anger of some protesting fans. If you go into the children's-book section of Eason's in Dublin's O'Connell Street, it's packed with Potterphenalia, but there's no room now, for example, for any of A.A. Milne's Pooh books.

But is Harry Potter, the literary figure, really worth all the reverence in the first place?

It's not begrudgery to suggest that it's too soon to assess the books' "lasting" value, nor to propose that Harry had some good fortune to emerge in the 1990s, at the height of the West's worry about children's minds being numbed by game consoles, PCs and satellite and cable TV. Before it became clear that the internet would be primarily a reading-and-writing medium (at least for the present), there was genuine concern about technology-induced illiteracy among young people.

Literature was crying out for a hero. Children needed something to read that would be both Fun and, almost by definition, Good For Them. J.K. Rowling came up with the goods, thanks to a brilliant pastiche of elements. They weren't unique - Jill Murphy, for example, had done something similar for younger readers with the Worst Witch series of books back in the 1970s, following a trainee witch through a succession of terms at Miss Cackle's Academy - but they were very cleverly combined by Rowling.

Psychologist Marie Murray says Harry Potter draws on children's "eternal fascination" with magic. "Chambers and goblets and magic potions and spells and the capacity to fly away from danger put children back in control of an incomprehensible or uncontrollable world," she says.

The basic Potter premise - orphan boy on the edge of puberty discovers his powerful gift for magic and is spirited away to a mysterious academy full of jealous peers and unlikely wizarding lessons - is a direct echo of the beginning of Ursula Le Guin's Earthsea trilogy.

But it's different. Harry is a perfectly unlikely hero - even his name reeks of English suburban nonentity status. (Remember Mr Pooter from the Victorian Diary of a Nobody? Or Henry Pootel, poor Piglet's scrubbed-up altar ego in Winnie-the-Pooh?) Rowling comicly domesticates the magic with a boarding-school narrative out of Enid Blyton - right down to the fact that each novel in the series covers a year in school.

Murray agrees that the Hogwarts echoes of Mallory Towers are part of the success of the Harry Potter books. "It's a repeat of a formula that was excellent in its time and that adults can relate to." However, she's not sure that the genuine appeal of the series can survive the consumerist hype: "It would be a tragedy if a good read turned into a bad fad. Saturating the market with images of Harry, pencil-cases, board games and toys brings 'habituation', the mechanism whereby repeated exposure reduces impact.

"Once the objects flood the market, the imagination of children will become jaded by the excess of images. The real readers will persist, because a good story is a good story, but the potential readers or generations of readers may fade away."

Fionnuala Kilfeather, chief executive of the National Parents Council (Primary), is a fan of Harry Potter and says "you can't blame a book for the merchandise", but she too is seriously concerned about the hype. "That sort of advertising aimed at children is highly questionable," she says. "Harry Potter is a very powerful medium, with a feature film backing it up. Advertisers wouldn't be spending zillions of pounds promoting these products to children if it didn't work."

Kilfeather has several nuggets of wisdom for parents. They should watch TV with their kids and talk critically about ads and products; parents should "look seriously at the play value" of the Potter toys and remember that research shows that having loads of toys is actually counterproductive to children's development. Ethical questions are raised, she says, when something like Harry Potter is used to promote products like Coke that run contrary to the Department of Health and Children's campaign to improve kids' diets.

Media education in schools could play a role, Kilfeather says, in containing the influence of Pottermania and its like.

However, at one school in Dublin's inner city, Pottermania is entirely to be welcomed. So says Finian McGrath, principal of St Mary's Place Boys National School, Dorset Street.

"I'm an old-fashioned teacher in a disadvantaged school. I have to come down on the side of something that's good for kids' reading, good for kids' writing and good for kids' imagination."

For his students, Harry Potter is essentially a new phenomenon. "I was a little concerned about the hype," he says. "But I've seen the results on the ground." Helped along by RT╔ Radio 1's Rattlebag, which asked two boys from the school to review the movie, St Mary's Place "is just buzzing about the film... And we have kids in our school now who want to write a book."

McGrath's school has 103 pupils, 15 per cent of whom are non-nationals, and many of whom have reading and learning difficulties. "Most of the kids start school here, at age four, already three years behind middle-class children in terms of reading readiness," he says. "We have to spend five years catching up, trying to get them into books and into reading."

In his own sixth class in recent weeks, McGrath has been "putting an Irish spin on it", linking Halloween, Harry Potter and the concept of the Bean Feasa. "We're going to do a series of stories about witches of the north inner city!"

Here, there isn't the luxury to complain about marketing and how movies might place limits on children's imagination. Harry is a hero, pure and simple, says McGrath. "Harry Potter has come along at exactly the right time for us."