With its expansive lawns and handsome red brick buildings, Abingdon school could be the setting for a Victorian costume drama, or a murder mystery of the kind Inspector Morse used to investigate down the road in Oxford. An unlikely breeding ground for social realist documentary makers, you might think. But this independent school is the alma mater of a film-maker of international renown. And the chance discovery of one of his earliest works in the school’s archives has inspired a new generation of filmmakers at the school.

When he was a pupil at Abingdon in the 1950s, Michael Grigsby ran the film club, showing not only popular feature films of the day but classic documentaries such as Night Mail. He became increasingly fascinated by these accounts of everyday life and resolved to make his own documentary.

After persuading the headmaster to buy a 16mm camera and a tape recorder, and using an old pram for tracking shots, he and a group of friends made No Tumbled House, an irreverent portrait of life at the school, in 1955.

Grigsby went on to direct award winning films such as I Was A Soldier, A Life Apart and Lockerbie: A Night Remembered - telling the stories respectively of Vietnam veterans, Fleetwood trawlermen and the residents of the Scottish town where Pan Am 103 came down - and carved out a reputation as one of Britain’s foremost documentary makers in the process.

Meanwhile, No Tumbled House was gathering dust on a shelf until last year when school archivist Sarah Dearne arranged for some cans of old film to be transferred on to video. When she came to No Tumbled House, she realised the soundtrack had been lost. The credits listed Michael Grigsby as director so, having no idea who he was, she wrote a short item for the school newsletter to see if anyone knew of him.

Abingdon’s head of drama, Jeremy Taylor, had been planning to start a filmmaking club. But when Michael Grigsby got in touch after seeing his name in the newsletter, the Abingdon film unit took on a whole new dimension. Grigsby reprised his role of 50 years earlier, organising screenings of classic documentaries and feature films, only this time accompanied by his own work.

He arranged for Larry Sider, of the National Film School, to give a masterclass, and for specialists in sound recording, camerawork and editing to visit the school. He also convinced the head, Mark Turner, to buy professional-standard cameras and recording equipment.

As well as technical expertise, Grigsby was keen to instil a philosophy before the pupils shot their first frames. His own work is distinguished by a naturalistic style, an attention to detail and the slow revelation of characters and situations. By comparison with the hand-held camerawork and jump cuts of much of today’s documentary making, it is hauntingly slow but undeniably powerful.

“It goes absolutely against the grain of everything you see on television at the moment and which the boys are exposed to,” he says. But the idea that permeates all his films, of “giving a voice to the voiceless”, was just as important, he says. “Abingdon is a privileged school and I wanted the boys also to be aware of the community and society in which they are living.”

In their portraits of an antiquated cobbler’s shop, the redevelopment of Reading, homelessness in Oxford, the morning journey to school, an autistic boy’s love of horse-riding, and the life of a new boy at the school, the six short films shot by the film unit echo the style and concerns of their mentor. “Without him we would definitely not have made the same sort of film,” says Mike Chilcott, 18, the soundman on Harry and Brian, the tale of two cobblers.

There are moments - in the close-ups of machines in Harry and Brian’s shop, or a discarded tea cup and saucer on the railway track viewed through the wheels of a passing train - that would not look out of place in one of Grigsby’s own films.

The experience has given the pupils involved, aged between 12 and 18, an appreciation of the effort required in filmmaking - around 10 days’ work for under 10 minutes of finished product. “It has been a steep learning curve,” says Paul Godsmark, director of Prospects, the film about urban regeneration. Next year’s films, Paul confidently predicts, “will surpass these by miles”.

By then, Jeremy Taylor hopes to offer the school’s facilities to 20 pupils from local comprehensives through the Oxfordshire independent-state schools partnership. “We feel we are at the start of a potentially long and exhilarating journey, and we don’t quite know where it is going to take us,” he says.

With funding of pound;30,000 from the school to buy equipment, editing software and to pay tutors, it has been a relatively low-budget production for Michael Grigsby. But he is convinced the value of it is something much greater. “I’d like to see this experiment translated into schools across the country,” he says. There are few better ways of learning to interpret the world, he adds. “Filmmaking is like writing a book or a piece of poetry; it’s a very personal experience. However much you teach someone, they have got to do it themselves.”

Selected films from the Abingdon film unit and Michael Grigsby’s No Tumbled House will be shown at the National Film Theatre on London’s South Bank tonight at 8.45pm in Masters and Pupils, part of the Grigsby retrospective season, which runs until June 25