Alesso Baldovinetti

In London's National Gallery hangs a young woman in profile, her yellow sleeve stamped with a design of palm fronds, set against a flat blue that gives her nowhere to stand. For a long time visitors were told this cool, precise portrait was by Piero della Francesca, one of the great early Renaissance masters. Only in 1911 did the English critic Roger Fry reassign it to a quieter Florentine, Alesso Baldovinetti.

Baldovinetti was born about 1425 into a wealthy Florentine merchant family and, by his family's own account, turned down the comfortable trade he was expected to enter in order to paint. He joined the city's painters' guild around 1448. His contemporaries prized him for exactness, a jeweller's care with line and a delicate feeling for colour, and he worked in paint, mosaic and fresco alike, techniques where a single wrong stroke cannot be undone.

Much of that fresco work has decayed or been lost, partly because he experimented with his materials and some of them failed over time. So the reputation now rests heavily on a handful of surviving panels, among them the lady in yellow, whose sitter has never been securely named, though one guess makes her a noblewoman of Urbino.