By Caroline Briggs BBC News entertainment reporter

All three of the main stars were taken aback by the welcome

But the world premiere of Harry Potter and The Goblet of Fire proved Sunday night was no ordinary night.

Leicester Square was transformed into a scene from the schoolboy wizard's latest adventure, familiar to fans of JK Rowling's fourth book as The Triwizard Tournament.

But perhaps more daunting for the stars than the fiery reception from a dragon was the gauntlet of reporters and fans who had flocked from all over the world.

Pottermania meant overcast skies and stubborn rainfall failed to dampen the spirits of up to 7,000 people who turned out see the three big stars of the film, Daniel Radcliffe, Emma Watson and Rupert Grint.

Each new arrival was heralded by screams of delight from fans, some of whom had camped overnight to catch a glimpse of their idols.

But one of the loudest cheers of the night was reserved for Madonna, whose surprise appearance with her daughter Lourdes drove the flashbulbs to a frenzy.

"I'm a big Potter fan, but I'm here for Lola," she said, nodding towards her nine-year-old daughter.

A fire breathing dragon welcomed the stars to Leicester Square

"Harry Potter is for everyone - adults and children. I think JK is brilliant, I love her. The books are clear and entertaining and smart."

Madonna did, however, have one confession tucked up her sleeve.

"I haven't read any of the books, but Lola has read them all. I just watch the movies."

Supermodel Claudia Schiffer and acting stars Kate Beckinsale and Rob Lowe were also at the event, rubbing shoulders with some of the many stars of the film.

Katie Leung, who plays Harry's love interest Cho Chang, Mark Williams who stars as Arthur Weasley, and French actress Clemence Posey, who plays the beautiful Vela Fleur Delacourt, cast their own spells over the crowds.

Producer David Heyman said he was amazed by some of the attention.

"It's raining, people are screaming, some people have been here since 10pm last night, it's madness.

"JK Rowling has written these books and we are making the films, but it's really down to her.

It's a wicked job and really good fun. I want to continue doing it forever Rupert Grint

"She has given us this material and people are so passionate and excited about it."

Emma Watson, 15, who plays Hermione Granger, looked every inch the classic film starlet in a vintage embroidered chiffon gown.

She revealed that the dress had once belonged to a 1920s screen icon, but did not reveal the identity of the mystery actress.

"This is a 1920s vintage dress made for a past screen goddess. I thought it was quite appropriate that I wear it," she said.

And she hinted that she may not be around to see out the full complement of seven Harry Potter films.

Madonna's daughter Lourdes revealed Ron was her favourite character

"I promise I am doing the fifth one, but each film is so huge and takes up so much time I just can't make any promises because I don't know how I'm going to feel in two years' time."

Rupert Grint, who plays the flame-haired Ron Weasley, was more forthcoming about the future.

"It's a wicked job and really good fun. I want to continue doing it forever," he said.

He also revealed that The Goblet of Fire, directed by Mike Newell, was his favourite film in the series so far.

"Ron is a bit more of a moody teenager in this one and I think he gets a bit jealous of Harry too," he explained.

Daniel Radcliffe - or Harry Potter himself - paused to take a sip of water after spending almost two hours weaving his way through the media and throngs of autograph hunters.

"It's partly nerves and partly me being just ecstatically happy," he explained apologetically.

Fans came from as far afield as Argentina and the US

"It's just a joy to promote a film that everyone is so proud of, and rightly so."

When asked how he felt to have grown up in the public eye and become one of the best known teenagers in the world, he was philosophical.

"It's very hard to define what a normal childhood is.

"I was on the set with a bunch of people who were all relatively stable, so to be around stable people when you are going through your weird, shaky teenage years is possibly the best background you can have."

Robert Hardy, who plays Minister of Magic Cornelius Fudge, said the reason Harry Potter was so popular was down to a simple five-letter word.

"Magic," he explained with a smile.

"Magic works for everyone. The world is full of magic. You are full of magic, I'm full of magic.

"That's why people love Harry Potter and that's why I love it too."