Are there miscarriages of justice in art history? Neil MacGregor believes there are. However great an artist, if his name is lost he will not receive a fair verdict from posterity. No exhibition will be devoted to his work; no books will be written about him; he will not even figure in indexes.

Among these neglected geniuses is the 15th-century painter known only as the Master of the Saint Bartholomew Altarpiece. He may have been Netherlandish or German; he may or may not have been a monk. On stylistic grounds an oeuvre of half a dozen paintings, three of them large altarpieces, are attributed to him, and from them a vivid, if hypothetical, personality can be built up: emotional, compassionate, observant, original, humorous.

All that is certain is that he was a great painter whose name, if known, would rank with Botticelli or Holbein. In A Victim of Anonymity, the Director of the National Gallery, London, corrects the judgment of history by demonstrating the power of this unacknowledged master. MacGregor makes us look closely at works that are all too easily passed over, showing us a peerless artist whose paintings derive their fame from nothing but their own superlative merits.