"Trained to kill with her voice, which was like a macaw taking off repeatedly from a steam catapult." That is Clive James's memory of a co-presenter on a television series that has been long forgotten by all save those who presented it.

James is making, not a personal criticism, but a striking image. When he gets into his stride, which is generally at the very beginning of his first sentence, there is no one like him. Some critics say that this is just as well; North Face of Soho can be - and indeed has been - parodied with the greatest of ease.

It is true that when he goes over the top, he disappears into the stratosphere. "The joint was jumping with ghosts, but like all ghosts they were the expressions of a mind in search of equilibrium": this, one of his less self-explanatory sentences, is part of a soaring, over-engineered, page-long paragraph in which he congratulates himself on toning down the exuberance of his prose. "If he's like this now," a reader unlucky enough to have missed the first three volumes of his Unreliable Memoirs will ask, "what on earth was he like before?" Having had articles at the back of long-forgotten student magazines which featured James's poems at the front, I can happily reply: exactly the same.

The third volume of his Memoirs left our Australian-born hero leaving Cambridge for the capital. This, the fourth, sees him taking his wisecracks and wise thoughts to Grub Street and Fleet Street; he reviews television, before finally making TV programmes and a better living. He writes poems, plus lyrics for the cerebral singer Pete Atkin. But, in spite of this impressive pounding of the typewriter, there was a potential flaw about the idea of his life story, pointed out by his agent: "You haven't done anything."

Fortunately, he can make a little go a long way and seem a lot. James's bons mots are bonnier than anyone else's. But what sort of person peers out through the hyperbole? James gets his self-criticism in first: "Those of us who have been granted a disproportionate ability to express ourselves may not always have the best selves to express." He admits to self-doubt, and describes being sacked from a student review and suffering a mini-breakdown. He took to his bed catatonically, "like Stalin when he got the news that the German army had invaded his country".

In other words, his self-doubt is greater than anyone else's self-doubt. That's not a personal criticism, of course.