THE SELF-PORTRAIT IS one of the most fascinating of the secondary disciplines of Western painting. It is certainly one of the most revelatory. Who am I? What am I? And, peering into that other world beyond the looking-glass, Where am I? The questions come thick and fast. Most painters do a self-Portrait at one time or another, if only as a student exercise, or as a convenience - for there is no model more biddable than oneself. Yet, whatever the painting's provenance, it inevitably grows into something more, because those questions are inescapable. For some of the greatest artists - Rembrandt, Van Gogh, Max Beckmann, Lucian Freud - the self-portrait became a lifelong habit and study in itself.

Ruth Borchard, who came with her husband to England from her native Hamburg in 1938 as a refugee from the Nazis, began buying self-portraits by British artists in the late 1950s. Her only rule was never to pay more than twenty-one guineas apiece. For the most part, the artists she