You always know when one of the first [“Harry Potter” movies] are on TV, because you’ll get a text message from one of your friends saying, “How high was your voice?” It’s like watching a home movie, in some sense. But you just remember because the audience sees the scenes as they’re written, but we remember shooting [the scenes] and all the stories that came around it. Like the Quidditch World Cup in [“Harry Potter and the] Goblet of Fire,” it’s like the Glastonbury Festival at Leavesden [Studios].