AFTER the hype, the mayhem. A fictitious green-eyed orphan with magical powers had Britain at his feet yesterday as his creator launched the most widely awaited book in publishing history at London's King's Cross station.

Parents scuffled and children wept as J K Rowling, the author of Harry Potter and the Goblet of Fire, was greeted more like a film star than a writer. She described the pandemonium surrounding her latest book as "complete madness".

"I wrote the book for me, this is all a bit of a shock and I'm amazed - think of a stronger word and double it. I thought about three people would like them, including my sister and possibly my daughter."

Rowling, dressed in a purple cardigan, patterned skirt and sparkly pink shoes, said that she had been "surprised" the book was so long: at 636 pages, the new hardback is more than twice the length of her three previous works. She said: "It was the hardest so far to write - it's a long book. It's the culmination of 10 years' work. There was a lot of external pressure this time. I put everything into these books. After my daughter, Harry is the most important thing to me."

Rowling, a single mother from Edinburgh, knew she had shattered the record for advance orders with five million globally even before she embarked on the nationwide publicity tour to promote the latest adventure of her hero, a bespectacled teenage wizard. Before leaving Platform 1 - transformed into Platform 9.75 in honour of Harry Potter's gateway to his mystical world - her fourth book was selling at the rate of up to 350 per hour in large bookshops.

There were angry scenes at King's Cross as two fathers pushed each other, their children wept and other youngsters, some dressed as wizards with broomsticks, sobbed because they could not get near the author for her autograph. Thousands of children - and many adults - began digesting Rowling's latest offering after an early-morning dash to bookshops began at midnight and continued for the next 23 hours.

A 200-strong crowd gathered outside Waterstone's in Piccadilly ahead of the store's midnight opening, which ended in a sleepover party for 50 children. Outside nearby Hatchards there was a 500-strong queue for its 8.30am opening, with fans stretched along the length of the neighbouring Fortnum & Mason store.

Archie Watson, 10, a Harry Potter lookalike who has applied for an audition as the Hogwarts School of Witchcraft and Wizardry's hero in the forthcoming Harry Potter film, said: "This latest book is enormous and I don't know how long it's going to take me to read it, but I'm not going to do anything else until it's finished."

There were similar frantic scenes early yesterday in America, where there is a record first-run print of of 3.8 million copies: 40 times as many as a typical bestseller. Sarah Watkins, the duty manager at Waterstone's on Piccadilly Circus - where a panel of young Harry Potter enthusiasts read the book for The Telegraph - said the scenes early yesterday had been frenzied.

She said: "It's the most desired book that I have ever come across in my five years in the trade. It's probably the first really, really total adventure story since The Lion, The Witch and The Wardrobe [by C S Lewis]. J K Rowling seems to have found the perfect mixture of fantasy and real life."