The distinctions between Masterpiece Theatre and Mystery! get fuzzier every year. Masterpiece leads off its new season with A Murder of Quality, a two-part, British-made murder mystery based on an early John Le Carré novel. The author adapted it for television himself, and Murder stars Denholm Elliott (Indiana Jones and the Last Crusade) as Le Carré's veteran character, aging spy George Smiley. But Le Carré fans will realize that this is atypical Smiley: He is literally on a sabbatical from spying here, curled up with a good book. Smiley is only reluctantly drawn into the murder investigation of a schoolteacher's wife, at the request of an old friend, played by Glenda Jackson.
There's pleasure to be gleaned from the methodical, self-effacing way Smiley goes about solving the crime at this posh English private school; Elliott's dour face and low rasp are put to good use in this pulling at his old overcoat, he turns himself into a sort of British Columbo. But it soon becomes clear that finding the murderer isn't really the point of this two-hour movie; the story is, as Le Carré has said, ''a frontal assault on the British private educational establishment.'' Murder teems with malicious caricatures of rotten teachers and bratty students, and although the plot occasionally seems aimless, this middling Masterpiece offers comfy escapism for both Anglophiles and viewers who always hated school. B