The Peter Mullan film inspired by costumed Harry Potter tour viewing Edinburgh grave

The Fall of Sir Douglas Weatherford tells the story of tour guide Kenneth, who dresses as his ancestor, the famous philosopher and inventor Sir Douglas Weatherford.

Director Seán Dunn, who grew up in Edinburgh, but now lives in New York, said he had been on a visit home with his wife and visited Greyfriars Kirkyard, where he spotted the costumed group of tourists looking at the grave of Thomas Riddell, which is reportedly the inspiration for Tom Riddle, the original name of Lord Voldemort in the Harry Potter books.

“I brought my wife over to see Edinburgh for the first time and we ended up in Greyfriars Kirkyard,” he said. “It had been a while since I’d been back and there were a lot of tours going on up there. There was a Spanish guy in a cape, with other Spanish people also wearing capes, looking at the Tom Riddle grave.

“Witnessing that and then also reading the grave of the real Tom Riddle which said he was a captain in the British Army who had died in Trinidad in the early 1800s, I thought that was an interesting bit of history, especially when you look at our actions overseas.”

He added: “That was the seed and it went from there. The comedy came from the absurdity of the situation of adults in costumes.”

He added that the character of Sir Douglas was one he had created in a previous script for a film that was never made.

“He just fed into the idea I had had,” said Mr Dunn.

Shot in and around Edinburgh, where director Mr Dunn grew up, the production travelled each day to locations from Yellowcraig beach in East Lothian, to the Pentland Hills. A number of locations, such as the visitor centre, as well as the pub which, in the film, was the former scientific laboratory of Sir Douglas Weatherford, were located in Balerno, near Edinburgh.

“The meta aspect of the shoot wasn’t lost on me,” said Mr Dunn. “We did take over the town of Balerno - at least one street of it - for a week, which meant that regular people couldn’t walk through. I’m sure they were getting impatient at our presence there, just like Kenneth does with the presence of the fantasy show in his town of Arberloch. But, on the whole, I think the locals did enjoy it.”

Mr Dunn, who went to Leith Academy in Edinburgh, said he had enjoyed filming close to home.

“It was amazing coming back,” he said. “I got to stay at home in my childhood bedroom while I was filming.”

The Fall of Sir Douglas Weatherford was supported in development and production by BBC Films, the British Film Institute and Screen Scotland, and is released by MUBI. It will be in cinemas UK-wide from Friday.