Michael Moore is one of that all-too-rare breed of conscience-plagued Americans whose revulsion at the state of their native land has driven him to make a lifetime’s work of taking the place apart, in print and on film, in the process yielding some of the finest, funniest, most illuminating political satire of his generation.

Though Moore’s new film Bowling For Columbine, as the title indicates, is largely about the grisly and upsetting business of the Columbine high-school murders, entire scenes of it still fill you with more laughter than a hyena on crack, while not at all evading the disturbing realities that emerge over the course of this freewheeling semi-documentary two-hour investigation.

Drawing an ugly parallel between America’s addiction to external violence and the mind-boggling rates of gun-related murder among its population, Bowling For Columbine will probably be preaching mainly to the converted on this side of the Atlantic – at any rate, after two hours, the case for more stringent gun-control is simply beyond argument. National Rifle Association spokesman Charlton Heston, unwisely granting interview time to a Moore in merciless mood, comes across as a noxious belligerent racist, while others such as establishment scapegoat Marilyn Manson and South Park co-creator Matt Stone crop up along the way.

However, our host himself is the star of the show by a mile. Profoundly Yank, in both appearance and manner, Moore makes for enormously engaging company. His obviously heartfelt political ranting demonstrates real American patriotism as opposed to the Arab-bashing jingoism so rampant this weather.

Truly essential viewing.