After seven months of secret negotiations, the movie contract with Warner Bros was finally agreed last week, amid much competition from other studios. The deal means that the phenomenally successful, award-winning story of an apprentice magician and his studies at Hogwarts School will be turned into a live action film - rather than a cartoon animation - within the next two to three years.
The director and cast of the movie have yet to be determined, but the search will soon begin for the right child to play Harry - a young orphan who is forced to live under the stairs by cruel relatives, until one day he learns that he is really the son of famous wizards.
The huge popularity of the book - which, along with its sequel, Harry Potter and the Chamber of Secrets, continues to dominate both hardback and paperback bestseller lists - will ensure that the actor chosen is immediately catapulted to star status. He is also likely (and here lies the rub for many readers) to be an American.
Ardent fans of Rowling's hero are already nervous at the prospect of the wholesale transportation of the story to an American setting. They fear that the cleverly pastiched atmosphere of a British boarding school will be lost in translation. And how, they wonder, will the mythical platform 93/4 at King's Cross Railway Station - a location that functions like the wardrobe in C S Lewis's Narnian Chronicles - be altered for US cinema audiences?
"It is essentially English in the way it talks about school-life. There is even a school game at Hogwarts which the author calls Quidditch and which they play on broomsticks," said Lulu Heathfield, a solicitor from Brighton who is enjoying reading the first book to her son, Orlando. "I suppose they would have to make it Ivy League or preppy if they set it in America.
"The story creates a whole world like Mervyn Peake or C S Lewis, and it is full of wordplay and witticisms that make use of European linguistic heritage," she said.
David Heyman, the London-based producer behind the film deal, says his own preference is for a British setting too.
"I hope to shoot it here because this is where the book is set," he said. "But I think it would work just as well over there. We have not decided on a director or cast yet; what comes first is finding a screenwriter."
J K Rowling herself, currently on a tour to promote the launch of the first book in the US, is to be closely involved with the development of the film, Mr Heyman confirmed.
"I fell in love with these books," he said, "even though I don't have any children. Other adults I have spoken to about the book have felt the same way. One couple read the book on holiday and ended up tearing it down the spine and passing the pages to each other one by one, they were enjoying it so much."
The first book was written by J K Rowling - aka Joanne Rowling - during snatched moments in an Edinburgh cafe called Nicolson's. A divorced, unemployed, single mother, without a home of her own at the time she started to write, the success of the two books has been a genuine rags-to-riches ride for the author. She still visits Nicolson's, however, and says she is now proud to buy more than one cup of coffee over a two-hour period.
Her publisher, Bloomsbury, has been quick to acknowledge the appeal of the 223-page novel for adult readers as well as children. This month it brought out a specially-designed adult cover for the book to run in tandem with the children's livelier jacket design. This is a stunt rarely pulled in the book world although Jostein Gaarder's Sophie's World also came out in two separate covers, aimed at different age groups.
In the US, the first book is being published by Scholastic, under the title Harry Potter and the Sorcerer's Stone and next year will be the leading title in the publishing house's book club, which reaches an estimated 47 million members.
J K Rowling, who plans four more titles in the series, is currently working on the third novel, Harry Potter and the Prisoner of Azkaban.