What was your last scene?
There were a couple. One of my last scenes as a group was us, 19 years on, on the platform at King's Cross. That was really quite fitting, because one of my first scenes was as a 10 year old being put on the train there, ten years ago literally to the day, so it was really weird and suitable that that fit. My very last one was a night shoot on 2nd unit just by myself. I was shot walking away after the battle, I believe, so again, that was really nice because there's always a tighter feeling with the 2nd unit crew.

Well, the crew have been with it as long as all the actors.
Yeah, and the 2nd unit even more so: a lot of them have been there longer than the first unit so we had a great time on that last shoot. Dom Fish, the first assistant director, gave me a very charming send off and I made sure that as soon as I got a wrap I was gone, because I knew I would start blubbing like a girl.

Did you have a favourite scene on this one?
The end battle is obviously the fight; everyone was looking forward to it and it was just months and months of ripping each other's heads off. Personally I was excited about the nineteen years later bit. I'm so grateful that Jo wrote me in that part, because I can't wait to see all of us when we're 40.

In the last film you've left school and you are very much in with the Death Eaters which means you get to spend screen time with some amazing actors. Have you learnt a lot from those guys?
Very much so! That was the cool thing about these last few films compared to any previous ones. I've always been in among the kids looking sneery, whereas in this one I was really the only child amongst the realm of evil. When you see that call sheet in the morning, it's great. You've got Alan Rickman and all these, literally, knighted actors and you think, "Oh my god". I spent two days in pure silence not saying anything to anyone out of pure fear! It was a very cool few days filming. Watching Helena was one of my favourites I think.

There was a lovely moment at the Empire Awards one year when you were both there and she immediately went into Bellatrix mode.
I always get really taken aback by that! It's all very different when you're working together, but when you're outside work you always think, "I wonder if they still have a clue who I am". And she literally pounced on me! I've learnt a lot from her. She's the complete Jekyll and Hyde, if you will: she's the sweetest British lady and slightly in her own world and then when the cameras roll she goes berserk, which is amazing. It's brilliant to watch. I could name more: every single one of those actors has been incredibly nice to me, which makes a big difference.

It's a really interesting journey for Draco through these films. When you leave him he's almost lost, something that he's believed in for so long has gone.
Yes, it's been swept out from under his feet. It's a really hard writing task: the idea is to spend six years getting the audience to dislike this character, to certainly have no empathy for him whatsoever, and then within two years to show how the bully is treated at home and why he is like that. You see him get put in a few unfortunate circumstances so I'm hoping by the end of it you really feel quite bad for the kid. Daniel and I have often talked about it as being two sides of a coin: Harry with all the great influences, look what he can achieve, and Draco with the exact opposite and trying to fight the fact that his parents couldn't be a worse influence. Let alone Auntie Bella and everyone else around the table!