Half-length portrait of a warrior saint, facing half to the right, his head turned half to the right. He is resting his right arm on a parapet and his left hand on his helmet. He wears black armour and a rich green robe with woven gold braids which billows out behind his back. His head is encircled by a halo. The subject is usually taken to be the warrior saint William, Duke of Aquitaine, to whom the church of San Guglielmo in Ferrara is dedicated, but there is no reason to exclude other warrior saints commonly depicted in Northern European painting such as George, Victor and Liberale. Indeed, in Dosso’s ‘Saint George’ polyptych, executed jointly with Garofalo and now in the Pinacoteca at Ferrara, the saint wears the same rich green robe with gold bands as is seen here.

The painting is a virtuoso-piece - the saint’s thumb, for example, is reflected in both his helmet and in his breast-plate - and it may have been inspired either by fifteenth-century Netherlandish paintings of armoured saints or by a lost Giorgione. The painting has spawned an extraordinary number of copies, many of which are Netherlandish, and in these the sitter is often erroneously identified as Charles the Bold. This is impossible; the halo around the sitter’s head is original and his physiognomy is unrelated to secure portraits of Charles the Bold, suggesting that a Netherlandish artist in Italy made an almost immediate copy and that the misidentification was wilful. Radiographs reveal numerous pentimenti in the hands, which were at one point interlocked over the helmet.

The painting appears in Pyne's illustrated 'Royal Residences' of 1819, hanging in Queen Caroline's Drawing Room at Kensington Palace (RCIN 922151).