His method is often described as "improvisation". But this is misleading. It suggests something serendipitous and uncontrolled, whereas in fact all Leigh's finished work is very tightly structured. Nothing is improvised on stage or camera. The improvisation comes much earlier, when he and his actors together create the characters whose interaction will form the story of the play or film. Leigh does this individually with each actor, building a complete character through traits of personality, language, clothes and lifestyle before introducing them to one another. Thus events and dialogue are sparked by the collision of autonomous characters instead of being given to the actors in advance by an omniscient author. Other directors use improvisation to explore and deepen actors' understanding of their roles: no one else starts with it. But the point is that Leigh, starting with nothing, ends up with a precisely detailed script. His credits used to say "devised and directed by Mike Leigh"; they now read "written and directed".
Of course, he is not quite sui generis. His method was influenced by people like Peter Brook and Ken Campbell. Paradoxically his finished product comes closest to Pinter, whose resonant sounding of the hollow poetry of banality is honed in the study, not the rehearsal room. Michael Coveney draws other comparisons, with Ben Jonson's comedy of "humours" and with Ayckbourn. But like him or loathe him - and you can loathe him either for creating patronising caricatures or reproducing the sheer tedium of ordinariness - Leigh is a true original. It is a pity his name does not lend itself to an adjective like "Pinteresque".
His surname, Coveney reveals, was actually changed from Lierbermann. His grandparents on both sides were part of that fruitful influx of Jewish emigrants from Russia that so alarmed the Tory Government of the day that it passed the 1902 Aliens Act to keep them out. Leigh rejected his Jewish inheritance as soon as he could; but Coveney has no doubt that it helped shape him. He grew up as part of the large, prosperous and self-confident Jewish community in Manchester, bourgeois but still outsiders. His interest in human oddity was stimulated by the extensive tribe of his bizarre relations. He disappointed his parents - both doctors - by failing to get into Manchester Grammar. Salford, however, more working-class and much less academic - suited him better. He played the lead in school productions of Gogol and Shaw, and remembers reading Look Back in Anger in the school library in 1956. He was 13, and had found his metier. Four years later he won a Rada scholarship.
The breadth of subsidised opportunity open to that privileged generation is brought home by Coveney's account of Leigh's first five years after leaving school. Between 1960 and 1965 he "not only studied at Rada but worked as an assistant stage manager in repertory, acted in films and on television, took a foundation year course at Camberwell Arts School while attending evening classes at the London School of Film Technique... and spent a year in the theatre design department of the Central School of Art and Design". He created his first play while employed at the Midland Arts Centre in Birmingham; and, in 1967, he landed a job as an assistant director with the RSC.
His face - or rather his methods - did not fit and he was quickly sacked. The next few years were his most difficult, struggling for the chance to devise shows in colleges and fringe venues like the Open Space and Traverse. It was a piece at the Open Space in 1970 - the excruciating, Chekhovian Bleak Moments - which marked his breakthrough. Albert Finney - another Salford boy - put up pounds 17,000 to make it into a film. Then Tony Garnett, exercising an artistic freedom unimaginable today, gave him a slot to make Hard Labour for the BBC, and he was away.
Coveney's is not a great book: his idea of criticism is more to berate Leigh's detractors - Dennis Potter, David Edgar, Julie Burchill, Pauline Kael - than to offer much interpretation of his own. But his account of Leigh's now very substantial oeuvre - some 37 films and theatre pieces, climaxing in the grimly Dostoyevskian Naked (1993) - is clear and helpful. It certainly sent me back to the video shop.