You might wonder if this is a story that needs retelling. Anyone even patchily familiar with the careers of Peter Cook and Dudley Moore will experience recurring bouts of deja vu as they read it. The early intimations of genius (Moore's being musical, Cook's comic); Jonathan Miller seeing an early Cambridge sketch and being deeply impressed by the line "Hello, I see the Titanic's sunk again" (which is still wonderful, and could only have come from one mind); the trajectories of their careers peeling away from each other; Cook's alcoholism, Moore's womanising; and their deaths, each of them horrible in their different ways. Etc, etc.

To which one could reply that this is a story that bears some repetition. It is one of the saddest stories: it's about love, really, and the death of love. Cook and Moore were the opposites that attracted: upper-middle class against working class; deadpan against buffoonery; tall against short. (And, if you want to get silly about it, Cambridge against Oxford. But Oxford may as well have been Mars as far as Moore was concerned, so outside his experience was it. For Cook, Cambridge was just school with knobs on, and fewer rules.) Look at the front cover, with David Steen's portrait of the pair, posed to maximise their differences. Of course, Moore is looking up to Cook, as he always had to when the latter was upright; but here – the picture is from the 70s – Moore's gaze is not the one familiar from their Pete and Dud sketches of the 60s, puppyish and liable to corpse at any moment, but appraising, and on the verge of beginning not to like what he was seeing. At the time, Cook was sliding fast into serious alcoholism, and Moore was, somewhat understandably, driven to tearful exasperation by this. Cook, though, has a glassy-eyed stare, a slight strabismus making it difficult to tell where he's looking or read anything into his gaze except a desire not to let on what he's thinking. It's nihilistic, and you can see how Cook strangely fitted into the punk/new wave zeitgeist later on; the Derek and Clive records were so remarkably and cruelly obscene that they made the Sex Pistols look like the Comets, and he presented, in the late 70s, the alternative rock programme Revolver. He was, as William Cook notes, very good at this, operating with the kind of high disdain that just about let everyone else into the joke – "more music to mow your lawn by", he said of one band – but the show was cancelled by bemused executives after only seven weeks and a run of poor press.

There were two more crucial differences between them: Moore was musically gifted, practically a genius; it took him about five minutes to understand jazz well enough to play it instinctively. Cook, however, was to all purposes tone-deaf, and had to be prevented from singing whenever possible. That was one chink in the seemingly unassailable reputation: the other, says William Cook, was his acting, which he never got the hang of, whereas Moore did. (I beg to differ, slightly, and offer as evidence the charming little swagger with which Cook, snapping his fingers, makes a parking meter run out of time in Bedazzled – it's a movement of grace and sexiness, which suggested him capable of better things.) Moore went on to become, as if in a boy's wildest dreams, a Hollywood sex symbol. For a brief while.

Accepted wisdom might claim that Cook's life in particular ended in failure, but when you've changed the course of a nation's comedy before you're out of your mid-20s you could wonder what is meant by "failure". This book is good at showing how important Moore was to Cook, without being condescending in the slightest. Moore's death you wouldn't wish on anyone: from an incurable disease which, as if by deliberate insult on fate's part, mimicked the symptoms of drunkenness.

Cook (William) is supremely knowledgeable about British comedy, and has interviewed many insiders. So read this and weep.

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