"I just love acting because it's the only thing I've really been good at," Dan says. "I have more confidence when I'm acting than when I'm doing anything at school, like writing and sports, which I've never been particularly good at."

Bashful Emma likes Destiny's Child and playing tennis. She is reading the Philip Pullman trilogy His Dark Materials and never wears make-up except during filming.

"My parents are very careful that I cling on to normality, and when filming is over I go back to school with all my normal friends and do everything that I used to do," she says.

And Rupert, who has left school, says of his fame: "I had no idea things would be this big, so it was a bit of a shock at first. But you sort of get used to it and it seems normal after a while. I get recognised occasionally but it's not too bad."

Like the others, he gets plenty of fan mail. "The most interesting things are the gifts that people send me," he says. "I get quite a lot of pyjamas. It's a bit weird."

"He (Ron) finds it really hard to get a date and he has some embarrassing situations when he asks girls out," says Rupert. "He's also really miserable because he's jealous of Hermione."

Emma smiles: "Hermione is totally swept off her feet and that's nice. She doesn't know what's happening to her."

"I learned to take the tank off and share air and clear my goggles and things like that," Dan says. "So after all that training I got the hang of it and I was pretty much ready to dive."

He did so well that for Christmas the stunt department gave him a diving log book containing a record of all the dives he did for the film and the time he spent under water.

"It came to more than 41 hours, not counting the training, so I was pretty pleased with that," he beams.

As an ever-changing cast of extras wait hours for the cameras to roll, they fill in the time by doodling in notebooks - and some of the girls' thoughts are X-rated.

"They tend to get carried away," laughs Tom Felton, 17, who plays Draco Malfoy.

Like his co-stars, Felton has grown since the first film, Harry Potter And The Philosopher's Stone. "The older he gets the more threatening and dangerous he becomes," he says. "He's a physical threat rather than being an annoyance."