Hampstead was the new Hollywood for one night only, as film stars including Brendan Gleeson, Jason Watkins, Phil Davis and Rosalind Ayres sashayed down a red carpet in front of the Everyman.

The paparazzi and film crews hoped to catch a glimpse of all the cast, although Diane Keaton, who plays the love interest for a Hampstead Heath recluse, played by Brendan Gleeson, could not make it.

Director Joel Hopkins, who grew up in Hampstead and is a New End Primary school alumni, said he was very much drawn to Harry Hallowes’ story, as a man who lived in a shack on the Heath – although the film is not Harry’s biopic.

Speaking on the red carpet, he said: “Harry’s story and Harry’s way of life inspired this film and the way he chose to live his life is the inspiration.

He added: “I grew up in Hampstead, so I felt particularly responsible to show Hampstead in a good light.

“It’s hard because I’m juggling between making a commercial romantic comedy and depicting a place that I love, so I definitely grappled with that, but I hope that I got the balance right.”

Harry Hallowes, or “Harry the Hermit”, passed away last year, having lived a relatively secluded life on Hampstead Heath from 1986.

He made headlines around the world when he was threatened with eviction from his makeshift shack, in the shadow of Athlone House.

Developers Dwyer Investments, who hoped to turn derelict Athlone House into flats, tried to gain possession of Harry’s grounds.

In 2007, Harry successfully won a legal battle and gained squatter’s rights.

In the film, there is a Ham&High journalist, who is sent to cover the community campaign to save Harry’s shack.

Mr Hopkins said: “I wanted to get across that the interest in him starts quite local – with the local press, and then it gets bigger and becomes more of a national interest story.

“The beginning of his protest, [the campaign to] save his shack, I thought we should have a local reporter in it.”

Brendan Gleeson, who plays the Heath recluse, said it was important for him to have Harry’s blessing for the film.

He first tried to speak to Harry when he was reading the script, but ultimately failed.

Lingering on the red carpet, Mr Gleeson said: “There was lashing rain, I went up to see if Harry would talk with me, he didn’t want to.

“It was one of the rangers who did the intermediary, and [Harry] wasn’t that interested in Hollywood, I respected him though.”

Mr Gleeson then wrote to Harry, and got a message back from a park ranger.

He described: “When I knew that the film was about to be made, I just wrote to him, because I didn’t want to do it behind his back.

“I was a little bit worried about invading his privacy, and I kind of got a message back from him that while he didn’t want to be part of it, he was glad of the courtesy of the letter and he was okay with it.”

Commenting on how elusive Harry was, Mr Gleeson said: “More power to him. I didn’t want to rock his cage.”