The three chums, having thumbed a ride on a bulldozer, arrived in Derry at the height of the Catholic civil rights marches and the Protestant "Apprentice Boys" parades. They had wandered into what was - despite the refusal of the British Government to recognise this in the three decades of violence that followed - a war zone. "It was all quite exciting really... like being in a film," recalled Sheila, a broadcasting natural in this, her debut broadcast.
Down in the Bogside the girls were caught up in the RUC's brutal attempts to crush the protests. But scarper they did not. Sheila was carrying a cheap Instamatic camera with which she took, naively more than bravely, a series of snaps. The photos have since acquired historical value. "This one I took close to here..." she trilled to a knot of small boys on a Bogside street, on her recent return to Derry with the producer Nigel Acheson, to make this exquisitely assembled feature, "...some children making petrol bombs."
Using the old photos was an inspired device with which to take the listener back to the human roots of the war. Sheila searched for the family that had sheltered these unlikely tourists when the nights rattled with gunfire. She searched for the little lads with the pavement petrol-bomb factory. And she found them. Dennis Gallagher, now a painter and decorator in his early forties, "got involved" (with the IRA) when thwarted Catholic demands for basic human dignities mutated inevitably into armed Irish nationalism. He served 14 years in Long Kesh "for explosions and attempted murder". Dennis has "no regrets", but hopes the current peace will hold.
His mum pinpointed the time he joined up: "Mammy," he said one day, "can I join the Scouts?" When she discovered young Dennis was doing more than learning to tie unnecessarily complicated knots and helping old ladies across the road, she felt only pride. "He was," she says, "fighting for his country". Denied jobs, decent housing and the vote, bullied by the RUC and "ethnically cleansed" by loyalist mobs who burned Catholic homes - with the assistance of those notorious police reservists, the B-Specials - it's no wonder that lads like Dennis joined up to defend their communities.
Even as a neutral observer, Laura watched, with tears in her eyes, an "Apprentice Boys" parade pass along a Catholic street. "I felt they were being so provocative," she said. Dennis Gallagher remembers, too, how the loyalists would throw small change down from Derry's city wall into the Bogside, and call him, his friends and his neighbours "peasants".
In the radio news reports of the time, many of which were cut into Sheila's narrative, these indignities were generally disregarded. Plummy-voiced BBC chappies - and it's amazing how even jobbing reporters sounded like minor aristos - chose to present the victims as troublesome agitators. ("Ah, there's one of the fire-bombs," purred one reporter airily, as a petrol bomb spun over his head).
On the night of 12 August 1969, Sheila returned to her Bogside holiday home after watching police break through the barricades defending Free Derry and beat up her new friends. She turned on the TV set, still believing that all the BBC said was true. "It was such an enormous shock," she recalled, "to sit down to watch the news and think, `this is nothing like what I've seen today'." Sheila's friend Pat, reflecting on their holiday 30 summers ago, said, "it was a lesson in history". As was this fascinating programme.