I was at a signing in a big store a couple of Christmases ago, and there was a group of children all coming up to chat to me and get autographs. Suddenly, one little girl, I looked at her, and she was terrified. Something behind me had frightened her. She was shaking. Real, utter terror. I looked round, and it was a Dalek! I stood up and said, ‘Don’t worry, I’m the Doctor, you’re safe with me.’ I didn’t do it for comedic effect. I did it for that little girl. I think it was the best piece of acting I’ve ever done.