When William Golding said to Nigel Williams that the latter's stage version of Golding's iconic novel, Lord of the Flies, would be performed at "the crossroads of great cathedrals", he probably wasn't thinking it might end up on an open-air stage at Regent's Park in London. On an early autumn night in a clearing flanked by trees, more than a quarter of a century after Williams' adaptation was first performed in his son's Wimbledon school by students, that's exactly where it's ended up.

Parties of school-children still in uniform, some clutching dog-eared paperback copies of Golding's 1954 tome about a party of boys who survive a plane crash on an uninhabited island, look initially overwhelmed by the authentic looking sight of a decapitated passenger plane splayed totem-like as part of designer Jon Bausor's set. The noise of planes coming into land that punctuates the action overhead adds an extra frisson to an already charged atmosphere for the next two hours of Timothy Sheader's touring production, which arrives in the indoor arena of Edinburgh's Festival Theatre this week.

In the end, however, it's the onstage action that captivates, as, freed from their social restraints, what would normally be everyday playground gang warfare becomes something altogether more tribalistic. As performed by a top-notch cast who look younger than their years, the experience is even more electric.

“The natural landscape is a really important aspect of the story," says Williams. “What Bill said about the book is that, as it goes on, the boys become men. Seeing it done outdoors in Tim's production, I think you really see that for the first time. I think it's a very clever and very clear production, and I think Bill would've been able to see that as well.”

Lord of the Flies was originally sent on spec by Golding to publishing house, Faber and Faber. Golding was working as a teacher in Salisbury, and after his book was rescued from the slush pile, very quickly went out of print. Only later did its exploration of civilisation slip into popular consciousness and become a classroom staple, possibly on the back of Peter Brook's 1963 film version and after the book's cache was increased even further when Golding was awarded the Nobel Prize for Literature in 1983.

The original idea for Williams to adapt Golding's novel for the stage came from Matthew Evans, now Baron Evans of Temple Guiting, who was the managing director and later chair of Faber and Faber, who published both writers works. While now best known for his Emmy-nominated script for 2005 TV drama, Elizabeth I, featuring Helen Mirren in the title role, Williams' first novel, my Life Closed Twice, appeared in 1977. A year later, Williams' play, Class Enemy, which looked at adolescent conflict in a South London schoolroom, was produced at the Royal Court Theatre. Given such shared interests, Golding and Williams seemed a natural fit.

“Matthew said, look, everyone's going on about this book,” Williams remembers, “wouldn't it be great to do it onstage. He also wanted to keep control of it, because there'd been unauthorised versions of it done, not out of malice, but they made Bill very angry, because he never got any royalties, so it was Matthew who commandeered it all.”

Williams visited Golding at his home in Cornwall, where a “hilarious” and epically boozy evening ensued, before Williams returned home to work on the first draft of the play.

“I wrote the first act and sent it to Bill,” Williams remembers, “and he was really sweet about it. But then I thought, 'I can't do this', and I had him on at me asking when he was going to see the rest of it. It's a really difficult book to adapt, because a lot of it is description, but when discussions do happen, it has to be significant.”

Williams eventually finished the three-act version that was performed at his son's school, where opening night was even more nerve-wracking than usual.

“The whole idea was to do this so Bill could come to see it and see what he thought,” says Williams, “and I remember Matthew coming up to me and telling me he'd never seen me looking so scared.”

A photograph of the original production is pinned to Williams' toilet wall, and captures a cast which included both the son of actor Ben Kingsley and Williams own son, Jack Williams, now a successful screen-writer himself on TV dramas such as The Missing.

“I remember it like it was yesterday,” he says, “all these kids in the picture aged somewhere between ten and twelve, but who are all about thirty-five now.”

Adrian Noble, then artistic director of the Royal Shakespeare Company, picked up on the show, and invited Australian theatre and opera legend Elijah Moshinsky to direct the first professional production of Lord of the Flies. Moshinsky took the potentially perilous step of drafting in real children to perform in his production.

“There were some people who said children can't act,” says Williams, “which is ridiculous. Some children can act and some can't, the same as adults.”

Williams' adaptation was eventually picked up by director Marcus Romer's Pilot Theatre company, who toured it extensively. Nothing, however, has matched the sheer scale of Sheader's Regent's Park Theatre production, which was put together by the same team who recently toured the stage version of To Kill A Mockingbird, Harper Lee's equally iconic novel which put a child's experience at the story's centre. Williams worked closely with Sheader when the Regent's Park production was first produced in 2011.

Since then, while Williams' latest novel, RIP, “a comedy about a bloke who wakes up dead,” is about to be published, he is also writing a play for his old school.

“The director, who's one of the teachers, rang me up and said he couldn't find the right boy to play the main part,” says Williams, “so he said they'd decided to make it an all-girl production.”

Given the use of a selfie-stick and the unavoidable twenty-first century shadow of jungle-based reality TV show I'm A Celebrity, Get Me Out of Here in Sheader's current production, might something similar be done with Lord of the Flies?

“Well,” says Williams, “my feeling about the whole casting thing is that anyone can play anyone. White people can play black people, black people can play white people, girls can play boys, boys can play girls, and so on. The only thing I would say about Lord of the Flies is that you can't have it being girls from a girls school, because it's very much about male violence.

“I don't think there's another novel that's been written since the Second World War that deals with such visceral and incredibly serious themes in the way that it does. It's not just about boys who become savages. It's about democracy, civilisation and fundamental philosophical questions about the world, and in theatre, if you get it right, that becomes something sharper and even stronger.

“It's a story about human beings, and it's about young children, who are faced with having to deal with eternity, and that's a pretty big idea for them to deal with.”

Lord of the Flies, Festival Theatre, Edinburgh, October 13-17.

www.edtheatres.com