Harry Potter star Daniel Radcliffe on love. loss and Diet Coke

Jul 8 2009

"No, it was about full fat Coke - apparently highway patrolmen in certain states of America carry two litre bottles of Coke around with them to wash blood off the roads... but hell, it tastes good, so never mind!"

It's this clear thirst for and love of knowledge that makes it so hard to distinguish Daniel, in the flesh, from his on-screen alter ego.

He admits that curiosity is a quality he's picked up from the wizard student.

"What's great about Harry is he doesn't take no for an answer, he doesn't accept what people are saying, he always questions things and tries to go beyond what people are telling him and in the end that is both the downfall and the salvation of his character," he says.

"I think curiosity is a lovely quality to have and just a lust for knowledge's sake. Also, what I think all kids have learnt from him is just the value of friendship and how important friends can be to life."

Harry Potter And The Half-Blood Prince, the sixth film in the highly successful franchise, once again pits Harry and his faithful sidekicks Ron Weasley (Rupert Grint) and Hermione Granger (Emma Watson) against dark forces.

With the evil Voldemort on the rise, the students at Hogwarts have to be ever more vigilant about who is among them.

Returning teacher Professor Horace Slughorn (Jim Broadbent) provides Harry with valuable knowledge about his former pupil Tom Riddle, a boy who would grow up to become a threat to the wizarding world.

There's also romance in the air, as Ron gets a new girlfriend, making Hermione jealous, and Harry kisses Ron's sister Ginny (Bonnie Wright) for the first time.

"It was weird, because I've known Bonnie since she was nine. I was 11 when she was nine, I hasten to add. It was weird, because when Katie Leung was brought in to play Cho (Harry's first love), we all knew she was going to be the love interest, but with Bonnie as Ginny, she was just brought in to play Ron's little sister, so it was kind of odd kissing her."

That said, Daniel claims he wasn't nervous about the scene. Partly because he had just been performing in a West End and Broadway production of radical Seventies play Equus, which involved getting his clothes off every night.

"I'd been naked on stage by that point, so there's not much else to worry you," he jokes. "But I later found out that Bonnie was nervous, so I could have been a little bit more sensitive about the whole thing.

"There's things on film sets which no one tells you, like for Christ's sake don't stick your tongue in! Luckily, I have never made that mistake, but no one tells you and you're too embarrassed to ask. Generally speaking, unless your co-star does, DON'T! It didn't stop me from trying though..."