Your own barometer is all you have to go by, and often what makes a good director is knowing when not to say something. On occasions you can find yourself on a film set where the person who is wearing the director's hat is only trying to justify his position.

The script is your map of the world, isn't it? And if someone knows that if it's well-written, you get all of the beats, it will tell you everything you need to know.

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.

The thing a drama school can't give you is instinct. It can sharpen instinct but that can't be taught, and you have to have intuition. It's an essential ingredient.

I tend to read non-fiction.

Interesting things come your way but as you get older, your lifestyle changes. I don't want to travel; I don't want to be in a hotel room away from my family.