The daddy of destruction

In the art world, Metzger's influence is more obvious. This year's Museum of Modern Art New York retrospective revealed the huge debt owed by Dieter Roth (1930-1998), an artist who tested materials (books, wood, even bananas and chocolate) to the limits of recognition, transforming-them utterly. And one needs only think of Cornelia Parker's exploded shed, Cold Dark Matter, to understand that Metzger's influence spans several decades.

Michael Landy's Breakdown (2001), when he pulped everything he owned, down to the shirt off his back, together with valued paintings by his artist friends, reveals a more direct line of inspiration.

In the early Fifties, Metzger was heading for a successful career as a painter. His teacher, David Bomberg, then working at Borough Polytechnic, was reputed to have favoured his work over that of other students such as Frank Auerbach and Leon Kossoff. But no evidence of that period remains and even the leading Metzger authority, Andrew Wilson, has never set eyes on any of the work.

Even details of Metzger's life are scarce. Wilson reckons that Metzger spent a good part of the Eighties and Nineties travelling through Europe - Paris, Amsterdam, Brighton - living in squats, thinking about writing a book about Vermeer. "He is the last of the itinerant, avant-garde artists, with no visible means of support," says Wilson.

Today, settled in East London, he has no telephone, and can only be contacted by post.

At 78, he is still practising as an artist, but, these days, his project is an archival one, gathering images of pivotal conflicts, such as those in the Middle East and the Holocaust, although McMullen's film reveals a copious sketchbook of skeletal landscapes.

The artist who emerges from the film appears slightly eccentric, apparently out of the loop, but a fiercely focused commentator on the human condition. Metzger is often to be seen around London; but not ingratiating himself with the glitterati of the art world. Over the years, I have become increasingly aware of a diminutive figure at public conferences or discussions on art, firmly planted on the front row, eyes fixed intently on the speaker.

From time to time, when it comes to questions at the end of the session, he will throw a brilliantly articulated question into the discussion that will completely wrongfoot the whole discourse, pinning speakers down and forcing them in a new direction.

That is what his art is about today - a quiet, subversive voice - and McMullen's film emphasises Metzger's thoughts, simply by letting the artist speak on a range of subjects. The documentary is a terse 30 minutes, although the DVD includes an additional two hours of unedited interviews.

Even when Metzger speaks of those early auto-destructive paintings, it is not a question of what the art looked like, or its fragmentary remains, but the effect of the action.

"The more holes appear, the more interesting the action," he suggests. The real work of art is not the painting, and its limited plane of representation, but the way the work signals what is beyond it itself; the viewer literally passes through it.

Metzger retains a remarkable faith in the power of art. "Today, the artist has the freedom to state the unacceptable," he claims. But despite the senior artist's influence on a younger generation, he is wary of those he calls the "sensation seekers" in British art, "people who are simply desperate to present their persona above their own art".

Ironically, by holding back his own presence in the world of art, Metzger has become one of its most enduring figures.