A regatta first created by an eccentric Georgian businessman brought fun and excitement to Keswick – and promoted a forthcoming adventure film that may become a modern classic.

Derwent Island House on Derwentwater was built in the 18th century by the wealthy entrepreneur Joseph Pocklington – known as King Pocky.

As part of his efforts to win over locals, he launched an annual Derwent Water Regatta for townsfolk.

Now the National Trust, which owns the house, set on an island on the lake, has recreated the event as part of an effort to celebrate and promote outdoor activity and water sports.

And in spite of overcast and drizzly weather, the weekend event pulled in hundreds of visitors – as well as more than 100 boats.

The revived two-day regatta, now in its four year, transformed the shores of Derwentwater into a hive of activity, with historical re-enactments, music, fell races – and a chance to see the boats that will feature in the forthcoming film adaptation of the children’s book Swallows and Amazons .

Many were thrilled to see boats bearing the book’s name, Swallow and Amazon, race, with one piloted by the film’s producer Nick Barton, whose previous successes include Calendar Girls and Kinky Boots .

Since Arthur Ransome’s book was set in the Lake District, much of the filming for the film was done at Derwentwater.

Nick explained that the film blends the book’s adventure with the real life – but until recently little known – life of its author, a former MI6 spy who once worked under cover in Russia.

“We started filming properly in 2010 and then filmed last year in the Lake District,” said Nick.

“It took me four years to find the right boats. We clearly wanted to work in this landscape. It’s unique.

“The sailing conditions are challenging but the scenery is fantastic and we definitely wanted to film here.”

The film’s world premiere will at the town’s Theatre by the Lake on July 24 – Nick’s way of thanking Keswick and the locals who helped. He added: “I think we’ve made a classic film.

“We intended to make a film which was faithful to the book, but Arthur Ransome was a fully paid up spy for MI6 when he was working in Russia, but of course he couldn’t write about that.

“Three weeks ago, we had a cast and crew screening of the film in London for the 400 people who worked on it, and the audience included members of the Arthur Ransome Society.

“The reaction was fantastic.

“One of the Arthur Ransome Society members said that the film told the story that he, Ransome, would have liked to have written. He didn’t, of course, write that story because he couldn’t.”

Also at the regatta were members of the Heart of Oak living history group, who gave demonstrations of canon firing – though they did not fire any actual canon balls!

“We’ve been firing canons which could send a 9lb canon ball half a mile from the decks of HMS Endeavour,” said Joe Batterham, from the group, whose uniforms date from the time of Nelson and the Battle of Trafalgar.

For former technology teacher Kurt Graham, 49, the decision to go to the regatta last year changed the course of his life. “I came here last year purely by chance because I’d seen it mentioned on the TV,” he said.

“I’ve done a bit of sailing and I fancied coming down to look at the boats. I saw the stall put up here by Fyne Boats, [based at Gatebeck near Kendal], and some months later I looked at their website.

“They were advertising for a workshop manager so I applied – and got the job.”

Jessie Binns, visitor experience manager for the National Trust, said: “We’re delighted that Swallow and Amazon are racing at the Derwentwater Regatta. “We’ve resurrected this historic Keswick event to encourage people to try a watersport for the first time.

“Arthur Ransome’s wonderful story of childhood adventures afloat has inspired generations of people with a fascination for boats, water and the outdoors, and that’s exactly what we’d like the regatta to do too. We hope people will come along and be inspired to get out on the water.”

The event was run in partnership with Cotswold Outdoor.