How was the big Yule Ball scene that you had to train for?

Oh, it was hard at the beginning, but everyone was so up for it, because the dancing sequence was so amazing that everyone wanted to learn it.

I must say that me and my partner Robert Pattinson (Cedric Diggory) were dire. The teacher would praise everyone except us. Then at the end we came out top. It was really hard because it all had to be co-ordinated.

What sort of stuff did you get up to outside of shooting?

Well, because we were all young, we had to study when we weren’t filming. They’re so strict with tutoring, that was like the top of the priority list.

But when we weren’t studying, holidays and stuff like that, we had a recreation room and there was ping pong, and a snooker table and telly and boardgames and everything. We just had great fun in there. We played Articulate and Connect Four; we’re all big babies.

Have you read the books?

Following the advice of my mother, who is a teacher, I had read the book a while ago, and I loved it. I got really really hooked. So I read the first 4 books – in French – and I am a huge fan.

Have you read them in English?

No, I’ve never read them in English. I think when you read in English and it’s not your first language then some of the funny magical terms are hard to understand. It’s the kind of book you want to enjoy, so I’d rather read it in French.

I never thought I would be in it. Then one day I was with a casting director in France that I knew quite well and he told me that he was doing the casting in Harry Potter. And he said “OK, come along, you may be too old for it”. But I still went and met Mike quite a while after that and that was it.