There's a YouTube clip of you at a shopping Mall in New Jersey, promoting the Half-Blood Prince earlier this year. There are hundreds of screaming fans – do you remember that? Is it a regular occurrence?
I’m not going to get that out of my head, it’s pretty rare. Without sounding too British, it was a sort of beautiful Americanness, they love to let go. I don’t think you’d ever get that sort of enthusiasm on our shores. My girlfriend was standing at the side of the stage, so I was just looking at her thinking, “My God, this is amazing.”

Where did you meet your girlfriend?
We met last year on Half Blood Prince - she worked in the crew.

Are you thinking about life after Potter very much?
The last year has been has been a real deciding point. I don’t think anyone really wanted to act for the rest of their life. It was a case of learning that we wanted to do it - and we pretty much all do. One thing we can all guarantee is the next thing we do is not going to be as big as Harry Potter.

Any specific plans in mind?
There’s possibly a Second World War film, I’d be an American soldier. That immediately appeals to me, being very different to Potter. There’s a surfing buddy film, which I’ve shot a teaser for. There are also rumours of a play, without jumping into Daniel’s shadow - I don’t think I’ll be getting the wand out.

Was there a moment when you realised acting was for you?
In the first five films, Draco was fairly one-dimensional. For the Half-Blood Prince I felt there was more weight on my shoulders. I had one-on-ones with Michael Gambon and Alan Rickman to role-play the scenes and there was a day with just me and David [Yates, the director]. I remember going home and thinking, “This is a very, very cool job.”

In a Times interview in July, Rupert Grint said “Being in Harry Potter is like living in a bubble, and it slightly hinders your independence”. Do you agree?
Dan, Rupert and Emma were the youngest when they came into it, and they almost live at the studios because they are needed every day. I was 12 when I started, so I already had a group of friends and they are still my best friends now. They were very uninterested in Harry Potter when it started and are probably less interested in it now. If I didn’t have that I wouldn’t have normality.

Have there been any moments when you’ve enjoyed the fame too?
In New Jersey, on the way out, there was that Beatle-mania thing where everyone was swarming the car. I thought, “This may never happen again in your life” so I decided I’d open the window and give a little bit of a hand shake or a wave. The window was down half an inch and someone’s hand grabbed my hair, and pulled me towards the door. My girlfriend gave it a good slap and that was that.