I had no idea, when I was first asked by my agents to audition for a film called Harry Potter and the Philosopher’s Stone, that it would be any different in terms of scale to the jobs I’d done previously. In my mind it was another Borrowers: a relatively high-budget film with lots of children and, if I played my cards right, a part for me. But if I didn’t get a part? That was okay too. It wasn’t the be-all and end-all. There was a good chance something else would come along.