Standing in front, the headlights give the impression that they're coming to get you. Its eyes, reminiscent of Herbie Goes Bananas, look cheekily uncooperative. The air is thick with magic and, when the photographer's flash starts misbehaving, I'm reminded that a muggle's place is not so near the Knight Bus.

In the film, the bus is doing approximately 35mph, weaving in between oncoming cars travelling at 10mph. "We had 30 stunt drivers," says stunt co-ordinator Greg Powell, "all of them the best in the business, and we recorded about four times as much footage as made it into the film." Those unseen sequences, included on the DVD extras disc, show the bus appearing to spin out of control after a handbrake turn at Bankside in London and a much-extended chase.