John Landis, director

We filmed the moors scenes in Wales. David Naughton and Griffin Dunne were inexperienced movie actors, but they gelled perfectly as two American backpackers attacked by a werewolf. But there was this moment when they were out walking – it was freezing and Griffin’s nose started running. He thought I’d called “Cut” but I hadn’t, so by the end of the sequence he was just wiping his nose and almost giggling. We left it in: it gave the scenes a wonderfully real feeling.

Halloween horror: John Landis's Monsters in the Movies - in pictures Read more

I wanted a weird, eerie ambience for the night shots. So that wolf howl you hear was actually made up of about nine different sounds, including a wolf, a lion, a panther, and even a locomotive. The other sound you hear, after that first attack out on the moors, was actually a pig farm, recorded from a distance. It was just something to make audiences say: “What the hell was that?”

My inspiration was the old 1940s horror movie The Wolf Man, starring Lon Chaney, in which – unusually – the werewolf was portrayed as a victim. Films tended to show the transformation from man to wolf through dissolves, but I wanted to capture how painful the entire process would be – and make it painful to watch. Although the film did have a lot of comedy, I wanted to treat the violence realistically, to make it as terrible as violence always is.

Elmer Bernstein wrote the score. It’s a big, bombastic, frightening piece of music and I’m delighted to be bringing it to Britain this month since audiences there really took to the film. Although the leads were American, it was a British movie: the entire crew and most of the cast were British. The climactic scene, set around Piccadilly Circus, is like a time capsule of London in 1981.

Facebook Twitter Pinterest ‘No fast moves’ … Naughton in London Zoo in American Werewolf in London. Photograph: Universal/Kobal/Rex/Shutterstock

David Naughton, actor

John Landis kept things very light on set, but the shoot was gruelling. When I met the special effects man, Rick Baker, I told him I was playing the werewolf. He said: “I feel sorry for you.” Rick was surrounded by these wild-eyed assistants who took moulds of my arms, legs and head. It was really suffocating. I remember asking them: “Are you sure you know how to do this?”

It was everyone’s first time, which was both thrilling and alarming. The transformation scene took an entire week to film, with me having to spend hours in makeup even just for a couple of shots. Things have changed so much in terms of digital special effects over the last 15 years, so I think the film has become a classic standard-bearer for the more practical use of make-up.

Jenny Agutter was a class act. I had a total crush on her since seeing her at the Royal Court David Naughton

Jenny Agutter was a class act. I’d been a student at the London Academy of Music and Dramatic Arts a few years before and had a total crush on her, having seen her playing the stable girl in Equus at the Royal Court theatre, where I’d been an usher.

As for running naked around London Zoo, in the scene where I’m in the wolf cage, the only reassurance I had was that the wolves had just been fed. But the handlers still said there were to be no loud noises or fast moves. “OK,” I said hopefully. “This will just be one take, so start rolling those cameras.” We were supposed to be done by 9am, but we overran. At one point, I looked up and said: “Wow! Why have you got all those extras over there?” They replied: “They’re not extras – the zoo’s open.”

• John Landis presents The Best of Elmer Bernstein at the Royal Albert Hall, London, on 18 June, with the Royal Philharmonic Orchestra conducted by Peter Bernstein.