J K Rowling | 'I've always been interested in superstitions and folk tales'

Jo Rowling’s first published novel, Harry Potter and the Philosopher’s Stone, was written in snatched moments in café s and at home, in the odd hours when her young daughter Jessica was asleep - and when she was not in a classroom teaching French.

Harry Potter first introduced himself to his author on a train from Manchester to London. "I don’t know where the idea came from," said Ms Rowling; "the thought of following a young boy through wizard school just fell into my head. I’ve always been interested in superstitions and folk tales, so they were wound into the tale as well."

She added that trains had always played an important part in her life - her parents met on a train from London to Edinburgh - and perhaps that is why Harry heads off for wizard school on the Hogwarts Express train. The school, while set in a fantasy world, includes many character types that she would have confronted at school. "They are all caricatures, but of recognisable types," said Ms Rowling. "If any one of those characters is me, it must be Hermione, which is rather awful. But I am sure that that is what I was like at that age - loud on the outside but with little self-confidence inside."

Ms Rowling [pictured right, in her 1997 author photo] was hopeful that Harry would be well received, but never envisaged just how well. Her first book in the series has just been bought by Scholastic’s us imprint Arthur Levine for a gratifying six-figure sum.

"I remember visiting Bloomsbury for the first time and being warned afterwards that no one makes any money out of children’s books. If I’d wanted to make money, do you think I’d have written about wizards?"

She said the level of success, with talk of film rights and further auctions and flattering comparisons to Roald Dahl, had yet to register. Ms Rowling gave thanks for the £8,000 grant provided by the Scottish Arts Council which had helped her complete her first book. She is now coming to the end of the second title in the series, and there will be another five books to cover Harry’s years at Hogwarts.

Ms Rowling said the first two titles took about a year each to write: "I spent a long time making notes before I started writing properly. I have boxes of notebooks all over the house, with the plots and ideas for the entire series."

She added: "I am very pleased that I have done that, or I might have been panicking by now that I would not be able to deliver. This whole situation is really quite daunting."

Ms Rowling said she knew little of the children’s publishing world, and that she tended to avoid reading children’s books.

Having heard her work compared to a Terry Pratchett novel, she said: "I can’t read any of his novels until I have finished my own. I would hate to find that someone else had already had one of my ideas first, and I would not want to be influenced by someone else’s writing. But it is something to look forward to reading."