I don't think the movie does credit - is that the right word?" "Yeah, 'credit' is okay, or you could say 'justice'." "Well, anyway, I don't think the movie does credit to the book."

Nine-year-old Louie would never claim to be the greatest Harry Potter fan in Ireland, but she's willing to have greatness thrust upon her. So here are the facts: since her best friend gave her a Harry-book two years ago and her mother read it to her, Louie has developed into a voracious and independent reader, with the almost constant companionship of Harry Potter; she has read each of the four novels repeatedly - Chamber of Secrets about five times, Prisoner of Azkaban more like "13 or 14 times", and the other two somewhere in between.

She admits the repetition can get "a little boring", but insists she always gets something new from the books. She chats especially brightly about Goblet of Fire, the "cool" way it subverts readers' expectations - killing an important character and "leaving Voldemort at the height of his powers".

The arrival of the Philosopher's Stone movie was something of a big deal to her: "My whole life has been leading up to this moment," she declared matter-of-factly en route to the cinema.

On the way home, the comments were less starry-eyed. "The things they changed were mostly really good, but they left some important things out."

She'd no complaints about the settings or characterisations. She adored Robbie Coltrane as her beloved Hagrid - and everything and everyone else was visually spot on, or close. She was thrilled to watch, at last, a game of quidditch in action. But she was disappointed that the storytelling wasn't quite so well looked-after.

With the movie hogging the headlines and playground conversations, perhaps reading Harry Potter confers a social advantage - but Louie doesn't see it that way. When she talks about the Harry-come-lately fans, her Dad's heart goes out, remembering what it was like to be a long-time Bruce Springsteen fan when Born in the USA came out. "Some of the kids go on about, 'Oh, I love Harry Potter, I'm so excited about the movie.' And then it turns out they haven't even read all the books - or they've just read them once."

All that repeat-reading obviously cuts into the time Louie might devote to other books. But at the rate she's going, even if every other book is non-Harry (and it is, give or take), then she's covering a fair range. Last week she started The Wizard of Earthsea, intrigued by its apparent role as an ingredient in the Potter pot; it was slow going, and she put it aside in favour of another crack at Harry Potter and the Chamber of Secrets.

Is Louie a merchandise market waiting to be tapped? "I don't really care about all that stuff. Okay, I have the books, of course, and the magazine and a couple of posters. And a pencil case. And obviously the Harry Potter duvet cover, that's okay. But most of those toys and little figures are just stuff you'll put in a closet and never see it again.

"I would like a Hagrid teddy though."

For Louie's six-year-old sister, Cara, the present hype, toys included, has helped turn Harry Potter from her big sister's stupid obsession ("I hate Harry Potter!") into a subject of legitimate interest. She enjoyed the movie enormously.

At one point Richard Harris, as Dumbledore, stands before a magic mirror that reflects the user's deepest desire, and he explains to Harry: "If the happiest man in the world stood in front of it, he would see only himself." Days after the screening, Cara was pretending to "write" a story that began with that image, and followed the subsequent misfortunes of the happiest man in the world.

Louie concludes, as if she were inventing the sentiment, "I think the best pictures are always in your head."