As a child growing up in the 1980s near Epping Forest in Essex, Garth Jennings was beguiled by Sylvester Stallone’s Rambo: First Blood and began making it, over and again, with school-friends and his father’s video camera. This formative experience was the basis for his film Son of Rambow, about two movie-mad boys growing up in suburban England.

“The stories tended to go out the window,” says Jennings, who wrote and directed the low-budget film. “It was just long fight sequences and lots of chasing, but I remember thinking: ‘This is the best thing ever!’ And I haven’t changed that much.”

Son of Rambow was always supposed to be his first film, but then Jennings, a former pop-video maker, landed the £30 million Hitchhiker’s Guide to the Galaxy first. That big-budget film-making experience, he says, was an important lesson in movie-making excess. “I don’t want to take anything away from Hitchhiker’s,” he says, “but it was confirmation that you didn’t need all that, well, stuff, to make a movie.”

Instead, Son of Rambow – shot for just £4 million, over eight weeks in Hertfordshire (the working hours were curtailed because of the school-age cast) – was a streamlined return to the film-making ethics established in Jennings’s childhood. “It was just me, Nick [Goldsmith, producer] and a tiny little crew,” he says. “It was much more hands-on, a dream shoot, the best fun ever. It shouldn’t matter how you make a movie, but we realised that, actually, it is important.”

Jan Pinkava, the animation writer and director, makes a cameo appearance in Rambow’s archival TV footage, as a nebbish adolescent prizewinner in the BBC’s junior cinema show Screen Test. For him, he says, the film is about “the yearnings of a child that are being made clear through the process of film-making”.

He identified with the main character, Will (Bill Milner), a cosseted child from a strict religious sect whose life changes after he watches a pirated copy of First Blood. “The point is that it’s about a boy who has a rich inner life, and suddenly he finds a way, through film, to express it, a way to come out into the world.”

Pinkava, who was Oscar-nominated this year for writing and co-directing Pixar’s Ratatouille, admits that his own childhood, like that of the boys in the film, was transformed by his Screen Test win, and that the encouragement and exposure he received from the show set him on a path that eventually led to Hollywood.

He adds, most importantly, that the type of childhood depicted in Son of Rambow – browbeaten, daunted by life yet pregnant with possibility – is something uniquely British on film. “You don’t see characters like Will in American cinema,” he says. “It’s a cultural thing, like Billy Elliot. It’s about the aspiration of the quiet child, the child who simply yearns is very different from the American Dream idea of the self-assured, go-getting kid.”

Jennings agrees. “I always knew that I didn’t want to make The Goonies, although at one point the script did resemble that kind of children’s action adventure movie,” he says. “I wasn’t going out of my way to paint any grim picture of childhood either. I just wanted to capture it as I remembered it, perhaps rather than as it was.”

The film, he says, is always hinting at the possible bleakness that lies just behind the characters’ jaunty lives. “I remember, as a kid, having a friend whose parents were always away for great lengths of time, and thinking: ‘Wow, you’re so lucky, no one tells you what to do!’ But it’s only now, when you look back, that you realise that those happy moments had underlying tragedy to them.”

Even now, with several studio projects bubbling under the surface, there is still something inherently childlike about his approach to work. “The very idea of doing it, of making a film, I still find incredibly exciting,” he says. “It hasn’t become a cynical thing, or just a job. I still feel the same way I did back when I was kid. I love it.”

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