Like many others, I have a little ritual on Saturday mornings. The moment the papers are delivered, I drop everything and riffle through the Times magazine looking for John Diamond's column. When it is not there, I wonder what his absence means. Is he merely sunning himself in Bermuda? Or has something more sinister happened?

For the past three years, since he was diagnosed with throat cancer, Diamond has been writing about his illness and the way it affects him, his family and his friends. There is nothing maudlin about these columns, and they are touched with the same intelligence and wit that characterised Diamond's work when he was more often to be found writing about wonky wheels on shopping trolleys.

I was not such a fan in those days, having a strong resistance to the idea of turning your whole life into journalism. Turning your own death - and death is what Diamond is staring in the face - into journalism turns out to be utterly compelling.

This stage adaptation of some of the weekly columns is no substitute for the real thing, but at its best it operates in exactly the same way as the original material by making you confront your own mortality. While he is waiting for the first of what will turn out to be many operations, he realises: "BUPA covers most contingencies but it doesn't cover fear." This is a typical Diamond sentence: it makes you smile and turn cold at the same time.

The weekly column is an unfolding saga, whose end may - barring miracles - be certain. And, like all our lives, it is a shapeless thing, a stream of consciousness. This stage version has the edge because it can shape and contextualise, so heightening the ironies. After all, there is something rather curious about a one-man show about a broadcaster who has been unable to speak since the removal of his tongue that nonetheless reveals him as an artful monologist. But then, this is also a man who is unable to eat but has a wife who writes cookery books for a living.

Robert Katz is not an actor, and it shows. But he gives a charming, self-effacing performance, never trying to impersonate Diamond, but rather presenting the writer and himself in parallel: two ordinary blokes of similar backgrounds - both Jewish, both with young families, both ironists - with so much in common and so much to live for. It is an evening with all the limitations of a one-man show. But the truth of the writing prevails. It will win Diamond more fans.