Laurie Lee country isn’t what it was. Heavy lorries snake through the ribbons of roads dividing the deep Cotswold valleys around Stroud; which can be annoying if you’re trying to reconstruct the authentic sound of Lee’s classic, Cider with Rosie.

But outside the old farmhouse where the Radio 4 recording crew is working, 12 children - aged eight to 14 - are engrossed and ignoring the distant traffic noise.

“Right, snowball fight,” says Jeremy Howe, the BBC director. “We’ve got a problem here: it’s going to rustle if you move around, as if you’re standing on...”

“Leaves and a path,” fills in 11-year-old Dan helpfully, looking down.

“Instead of snow. Right. So stand still, and pretend you’re rolling a snowball and throwing it. And you’ve got to sound cold.”

“But I’m not cold,” says Alex innocently.

“You’re acting cold,” says Howe. “Ever heard of acting?” To us it’s February, and the only robin to be seen is hopping about among snowdrops and catkins. But for these children it’s a snowy Christmas 90 years ago. A large fluffy microphone dangles over their heads as the cacophony begins.

“OK, stop,” interrupts Howe. “That was pretty bloody terrible. You’re treating it as if all the lines are surprising you. Start again. Go.”

“It’s starting to rain,” worries Viv Beeby, the producer, as a helicopter clatters overhead. But Howe’s still concentrating, listening as the noise of the snowball fight - “Got ya! Right in your face!” - fades into a mournful rustic rendering of “Good King Wenceslas”.

“Well, that’s very roughly it,” he mutters. “We’ll do it again.”

The children are a key part of the BBC’s new two-hour adaptation of the book, to be broadcast next month and released on tape. With a core of adult professionals, including Niamh Cusack and Tim McInnery (of Blackadder fame), and meticulously accurate sound-effects, they give people this new account of Lee’s childhood. “We wanted authenticity: children with local accents, and a range of voice and tones,” says Viv.

“So we auditioned in two Stroud schools, Archway and Rodborough. We recorded in a 1901 schoolroom and a farmhouse with a flagstone kitchen - the acoustics do matter. And we’ve stayed faithful to the text, though we’ve taken a few liberties in the sequencing.”

Jeremy Howe adds: “We went for schools we knew had good drama teaching. These kids haven’t lost their enthusiasm. You have to work with that; you can tell them how to be, but you’ve also got to let them be themselves.”

And so has the accent: though for the children this is optional. “I can slip into it, though it depends who I’m talking to,” admits Jen, 14. After a week’s recording, she’s at ease playing a rustic Gloucestershire girl. She sees nothing odd about using a sophisticated medium to tell a story of isolated, impoverished country life.

Because although these children are as media-savvy as any, they’re also tied in with the place and its past. Dan, from Slad, remembers Laurie Lee, who died last year; his friend’s friend’s great-auntie was Rosie herself.

As they shout and fight on the hillside, it’s easy to see in them the Laurie and Rosie of nearly a century ago, stripped of nostalgia and revealed as irreverent, noisy, vividly alive. Any city class, dozing through the book’s bucolic recollections, will be tempted to sit up and listen. Maybe, after all, there was more to Edwardian country life than roses round the cottage door.

“Cider with Rosie” will be broadcast in two parts on Radio 4 on April 12 and 19 at 3pm