Biography: For many years, it pained Christopher Isherwood to be associated with Cabaret. He refused to see the stage musical derived from his two most renowned novels, Goodbye to Berlin and Mr Norris Changes Trains, writing in the privacy of a diary that the production "sounds Jewish beyond belief" and writing to a friend that "I try to keep as far away from it as possible.
It's an ill bird that fouls the nest where the golden eggs are laid". But the prospect of those golden eggs eventually caused him to change his mind, and by the time a film version of Cabaret was being considered, Isherwood volunteered to write the screenplay. When the film was made - although not to Isherwood's script - he gloried in its critical and commercial success, willingly posing for photographs with the actress Liza Minnelli. In the struggle between high-mindedness and high earnings, the latter won every time.
Biographer Peter Parker probably didn't intend to display quite so many of his subject's flaws, but in a book of this length it was almost inevitable. Isherwood lived into his early 80s and for much of that life he kept a diary, a lot of which has already been published in three fat volumes. They reveal what is only further confirmed here: that their author was vainglorious to a ludicrous degree and that, like all self-centred people, he understood himself very poorly. How else could it be that only belatedly Isherwood became aware that an interest in exploring himself lay at the heart of all his fiction. Whenever he strayed from this topic, the work suffered. Nobody fascinated Christopher Isherwood as much as Christopher Isherwood.
In the early books, and specifically those two associated with Berlin, his crystalline prose style managed to conceal that character flaw from readers. It was less successfully hidden from friends and family, most specifically from his mother, Kathleen, who was abominably treated by her elder son even while he persisted in behaving as though he were the victim. Isherwood, born, like Evelyn Waugh, a century ago, in 1904, came from affluent English gentry stock but he preferred to ignore and professed to despise this background. His father died during the first World War when Christopher was still a child and he was largely raised by his mother. On reaching adulthood, he belittled and insulted her for no other reason, it would seem, other than that she represented the old, conservative world that Isherwood wished to reject. His mother's principal, if not only, fault, was that she had been born into another era and had outlived her moment.
Despite his best efforts, so too did Isherwood, but in the 1930s he could have no knowledge that this would be the case. On the contrary, for a heady period, he seemed to encapsulate the furthest outreaches of modernism; in Enemies of Promise, published in 1938, Cyril Connolly, the most astute critic of the time, hailed Isherwood as "the hope of English fiction". Where did that hope go? Well, early the following year, accompanied by W.H. Auden, it took a boat to the United States and remained snugly there for the duration of the second World War. Isherwood would later attempt to excuse his passive status during a bellicose period by explaining that a former lover "is in the Nazi army. I wouldn't kill Heinz. Therefore I have no right to kill anybody". As an argument, this is weak stuff, especially since the beloved Heinz does not appear to have reciprocated by agonising over the possibility of killing surrogate Christophers. Actually, what becomes apparent from Parker's biography is that Isherwood preferred to pick his opposition with care; for example, his mother who persisted in loving, and worrying about, her recalcitrant son could be repeatedly subject to verbal assault. But when faced with the threat of real opposition, Isherwood turned out to be something of a coward. In 1949, this supposed champion of gay rights was caught up in a raid on a bar in California and in order to escape any chance of prosecution opted to tell the police that he was not homosexual. So much for the fearless honesty he prized.
Essentially, Isherwood was a fraudulent rebel, declaring that the outsider was "one of the most socially valuable people in the whole community" but still proposing that he "must always go along with the other people as far as he can possibly manage to go". As a result of this fundamental dishonesty, he emerges from Parker's book, as he does from his own diaries, without much honour or respect. Which is not to propose that this biography should be given scant attention. It suffers from being much too long for its own, or the subject's, good. Surely no one of the stature of Isherwood - at best worth classifying as one of the last century's major minor writers - merits more than 900 pages? Parker produces admirable prose, he writes amusingly, he is unfailingly informative, he avoids repetition of information. But he cannot avoid repetition of characterisation, particularly when it comes to someone like Isherwood who was naturally inclined to behave in the same way over and over again. The reader's interest is therefore likely to be sustained less by the central player than by incidental characters such as Gerald Hamilton (the inspiration for Mr Norris) and by the pitiful saga of his younger brother, Richard Isherwood, whose sad story is eloquently told. A lesser book would have made a better one.
• Robert O'Byrne is a writer and critic