Felton grew up the youngest of four boys

But in the flesh, Felton, 23, is funny and charming and his hair is light brown. After filming finished, he was allowed to get a tan. For 10 years he has been wearing factor 50 to preserve his ghost-white complexion.

He is officially the sexiest Potter actor. Emma Watson, 21, admitted last week she fell for him when she was 11: "He was my first crush. He totally knows. We talked about it - we still laugh about it. We are really good friends now, and that's cool."

When I quiz Felton today, he says it was more a brother-sister relationship: "It was nine years ago. We were quite different in age group, and it's nice that we've been good friends ever since, and we've always been able to look back and laugh. It's a true sign of how long we've actually been spending time with each other, and how we've grown up together."

In fact he confesses his screen crush is Helena Bonham Carter, who plays his aunt Bellatrix in the films. "She is completely unique, an English rose with a crazy twist. She wears vintage French clothing and she's very cheeky. Off the set it's all hugs and darlings, then when the camera starts rolling she turns into a complete psycho. It's amazing to watch."

In real life, Felton has been with girlfriend Jade Olivia, 23, for four years (they met on Harry Potter where she was working as a stunt co-ordinator's assistant). She has a cameo in the final film, Harry Potter And The Deathly Hallows: Part 2, where we get a flash-forward to what all the characters look like in 19 years' time. Jade plays Astoria Greengrass - Draco's wife. "We had to slightly twist her arm. She'd rather be behind the camera."

He initially auditioned for the role of Harry, losing out to Radcliffe. "People think there must be jealousy but there honestly isn't, because no one could touch the part that he plays; not just for the acting but all the other stuff he has to deal with."

This week Radcliffe talked frankly about giving up alcohol when he realised the pressures of fame were making him dependent on whisky and partying.

It's a typically brave gesture, says Felton. "I've always been very proud of Daniel. I confess to having no knowledge of his drinking whatsoever, this is all news to me. But Daniel is always someone who's outspoken and fairly keen to get his message across, so I think it's great he's willing to talk about things like that. He's a massive inspiration to millions of kids across the world, he's always been wise beyond his years."