What happened to the British film industry? A quick examination would prove that it's still there, but it would be necessary to add the proviso that these days our studios largely exist to serve American film-makers. Profits are up, everyone's busy and next year's order books are full, so why should we complain? Perhaps it would be best to ask the British directors whose creativity helped to define the national psyche on film. John Boorman, along with David Lean, Carol Reed, Ken Russell, Jack Clayton, Lindsay Anderson, Tony Richardson, Joseph Losey, Bryan Forbes and John Schlesinger, to name just a few, belong to a golden age that lasted almost two decades, ending in the late 1960s.

During this period, a new breed of homegrown director flourished: someone who could achieve commercial and artistic success with a confident style of intelligent filmmaking. They were directors with faces, who imprinted their films with their personalities. Few of them survived the UK industry's falling impetus, or managed to bury their individuality deeply enough to please the Hollywood majors, and few are with us now.

Certainly, Boorman's biggest successes are mainly to be found in his early career, but in recent times he has reinvented himself as a terrific documentarist. Money Into Light, his diary of the production of The Emerald Forest, illuminated the pitfalls of transferring personal visions to film with style and good humour, but one always sensed that a biography would be forthcoming, if only because of the tantalising glimpses of Boorman's mind that could be gleaned from his films.

Adventures of a Suburban Boy is a loosely linear passage through Boorman's movie-making life, from his hideously chirpy pop picture with the Dave Clark Five, Catch us if You Can, to the high point of his late success, Hope and Glory, and one quickly realises just how personal the journey has been. Storytelling and the desire for dramatic resonance run in the family, judging by the photograph his mother, Ivy, recreated with her sisters three decades after its original was taken (it was recreated again on film for Hope and Glory, Boorman's cinema à clef); yet she was shocked by the intimate revelations of that film, which chronicled her son's schoolboy years in the adventure playground of their blitzed home in Carshalton.

This award-winning 1986 movie crops up throughout his memories as a defining moment. Boorman's war was a wonder, a thrilling, mythical embodiment of the common good opposing evil. He has always been fascinated by fantastical heroes, and it is this trait more than any other that gave him American appeal. His attendance at Catholic school and subsequent fascination with all things Irish has, by his own admission, had an insidious influence on his life and work, provoking him to a righteous indignation that has often translated into filmic images both poetic and violent. The gentility of his upbringing was mitigated by elements of anarchy and irony - he was aware of his mother's lifelong devotion to his father's best friend - but the real puzzle is why so many of his films are only partially successful.

There were resounding hits: the menacingly enigmatic Point Blank, Lee Marvin's career peak, and Deliverance, the heart-of-darkness trip into the shattered American dream. These were both by screenwriters of renown, but other projects foundered more badly than Boorman is quite prepared to admit. The risible, ill-conceived SF epic Zardoz became memorable more for the sight of Sean Connery in Zapata-moustache, suede thigh-boots and nappy than for its roots in Catholic parable, and was followed by Exorcist 2: The Heretic, a metaphysical thriller which proves once and for all that films about goodness have no dramatic tension. Excalibur, a kind of new- age Arthurian panto wrecked by a chromium-pated scenery-chomping Nicol Williamson, was virtually laughed out of the cinema when I saw it, but Boorman's lack of embarrassment is refreshing, and he's happy to tell anecdotes against himself - and Hollywood.

Adventures is filled with tasty brief asides: Mae West won hearts by saying "Loved your movie" to everyone she met; conflicts emerged on the Deliverance shoot that mirrored the story's characters; a Tolkien-approved version of The Lord of the Rings had been planned casting children as Hobbits; and the sexual insecurities of actors are casually (if not ruthlessly) exposed. This is the juice that every good film biography needs.

The tale-telling is effortless, memorable, highly subjective and occasionally unreliable, but Boorman is the director, and attention must be paid. He's a smart observer of California, with a keen outsider's eye. Christopher Isherwood drew his attention to the graceful American habit of ameliorating any situation: "He had just visited a friend in hospital. The nurse said 'I'm afraid your friend is not doing too well.' Isherwood asked if he had had a relapse. 'It's a little worse than that. He passed away.' "

Boorman shares Isherwood's maxim that the movies are a refracting glass slid between conscious and unconscious, and longs to make films about other realities born of magic and imagination. He can be accused of having pursued the metaphorical too blatently in his scripts, of being a tad unfashionable in his tree-hugging hippiedom, but his sense of visual grandiosity has rarely faltered, and he has always revealed an open heart. In this sense, Hope and Glory remains his most perfectly realised achievement, because it refracts a dark event through innocent, optimistic eyes to glorious effect. Boorman is the last of a select group granted the power to realise personal visions, not without flaws but with an immense depth of human decency, and for this reason alone, his biography is essential reading.