Leonardo da Vinci may have included secret self-portrait in 'The Last Supper'

The Last Supper: James the Lesser/Leonardo, second from left. Thomas/Leonardo, sixth from right, with extended finger (Rex Features)

Art historians have long wondered: what did Leonardo da Vinci look like? The Renaissance genius left no youthful self-portraits, but experts have long suspected that he may have inserted his likeness into one of his own works. Now one author has proposed a tantalising new theory – that Leonardo actually depicted himself, twice, in The Last Supper.

Ross King, author of Brunelleschi's Dome, believes that he used his face for the apostles Thomas and James the Lesser in the 500-year-old mural in Milan. His evidence lies partly in a little-known poem written in the 1490s – just when Leonardo painted The Last Supper. Its author, Gasparo Visconti, was a friend of the artist.

Visconti mocks an unnamed artist for putting his self-portrait into his paintings – "however handsome it may be" – and with his own "actions and ways", namely gestures and expressions. Visconti's poem lampoons the painter who "holds firmly in his mind his own image" and "paints none other than himself". The pointed finger gesture adopted by Thomas in the painting was viewed by contemporaries as a Leonardo trademark. Dr King also points to a red chalk drawing believed to depict Leonardo around 1515, sketched by one of his assistants. In The Last Supper, Thomas (to the right of Christ) and James the Lesser (second from left) are reminiscent of that image.