Edinburgh Fringe 2014: Heard the one about the tour guide comedian?

Comedian John Kearns's dark surrealist style, described by one critic as an elastic band about to snap, is not to everybody's taste. "Sometimes," he says in one routine, pointing to his own head, "I feel my body's a war memorial for a war that's still going on up there."

He performs his stand-up routine with reluctance, wearing a monk's tonsure wig and ill-fitting false teeth which he describes as "a joke that got out of hand" that he is now powerless to stop. But yesterday he had the last laugh when he was crowned the funniest comedian at the Edinburgh Fringe.

The former Houses of Parliament tour guide beat six other shortlisted comics to win the Foster's Edinburgh Comedy Award, formerly known as the Perrier, becoming the first Free Fringe act to win in the 34-year history of the prize.

Kearns, 27, from south London, scooped the best newcomer award last year and is the first person to win both prizes back to back. His stand-up show Schtick was described by one critic as "weird mainstream", and by the awards' producer, Nica Burns, as "utterly original, completely captivating and very, very funny".

Peter Buckley Hill, who established the Free Fringe a decade ago, said: "If anybody had ever doubted that we are the major force on the Fringe, they can doubt no more."

Accepting the £10,000 prize from last year's winner, Bridget Christie, Kearns made an impassioned speech about the future of the Fringe, telling the audience that it "has to change". Referring to the crippling cost of staging even a stand-up gig at the festival, he said: "The Fringe needs to look after comics because so many are struggling to put on shows."

At the main venues, comics pay thousand of pounds for performance space rental, marketing and PR. On the Free Fringe, comics pay nothing for the venues, which make their money from bar sales. A third of the 646 shows up for this year's comedy awards were on the Free Fringe.

"The Free Fringe helped me [to stage a show] when no one would touch me," Kearns said. He refers to his old job as a House of Commons tour guide just once in the show. But he said his experiences may feature in future shows. "I have huge respect for the institution so I wouldn't take the mick out of it – but yes, there are stories to tell," he said.

The best newcomer prize of £5,000 was given to Alex Edelman, 25, an American living in London. The £5,000 panel prize, awarded to a person or organisation that embodies the spirit of the Fringe, went to Funz and Gamez, a children's party games show devised by Phil Ellis.