Change is vital to any actor. If you keep playing lead after lead, you're really gonna dry up. Because all those vehicles wean you away from the truths of human behaviour.

And of course I've got kids of my own now, and they love me being in the Harry Potter films. I'm now part of a phenomenon. You become incredibly cool to your kids, and you get a young fan base. So you became the cool dad at school. You're suddenly hip.

Rather like Batman, I embody the themes of the movie which are the values of family, courage and compassion and a sense of right and wrong, good and bad and justice.

And of course I've got kids of my own now, and they love me being in the Harry Potter films. I'm now part of a phenomenon. You become incredibly cool to your kids, and you get a young fan base. So you became the cool dad at school. You're suddenly hip.

'Nil By Mouth' was a bit autobiographical, but as I always pointed out at the time, that's not my dad.