Giovanni Antonio Boltraffio, 'Portrait of a Man in Profile', probably about 1500

Boltraffio is known as Leonardo’s best student, and was particularly praised for his portraiture. Isabella Sforza, the wife of Leonardo’s patron in Milan, the Duke of Sforza, wrote that Boltraffio was ‘highly skilled’ in this area.

The profile view was a formal pose derived from medals, which themselves resembled ancient Roman coins. Its use here is unusual, as most of Boltraffio’s surviving portraits adopt the three-quarter view that Leonardo had popularised in Milan. Perhaps the sitter specified this view: although it was outdated at this time, it remained fashionable with some patrons in Milan long after it had gone out of favour in the rest of Italy.

The man’s face is further obscured by his cap, which is pulled right down over his brow. His right hand encircles his chest and rests tucked into his tunic, a pose that was favoured in portraits of this period. The dark colours, subtle contrasts and the use of shadow to describe the shape of the face are features of Leonardo’s style.

That Boltraffio made this picture has never been doubted. The identity of the man, however, has been the subject of plenty of debate. At one time it was thought to be a portrait of Gerolamo Casio, a poet from Bologna. Boltraffio painted two other pictures of him – the two were friends. They met in Bologna and Gerolamo mentions Boltraffio in some of his sonnets. Boltraffio was in Bologna in around 1500 and he painted an altarpiece commissioned by the Casio family which includes a profile portrait of the poet, kneeling in prayer before the Virgin and Child. The two profile views share the man’s large jowls but the hair colour is quite different. Portraits of Casio show him with reddish-brown hair whereas this man’s hair is certainly (and was originally intended to be) black.

This portrait has a long history with the National Gallery. The Gallery’s first director, Sir Charles Eastlake, saw it in a private collection in Italy in 1855 and described it as a ’stern-looking' man. Several years later it was purchased by his successor, Sir William Boxall, for his personal collection. He left it to Eastlake’s wife, Lady Elizabeth, on his death. It was eventually purchased by the chemicals magnate, Sir Ludwig Mond, whose collection entered the National Gallery in 1924.