A sketch of a “melancholy and world-weary” bearded man has been identified as Leonardo da Vinci.
The picture is believed to have been drawn shortly before the famous artist’s death in 1519, and it is going on display for the first time in the Queen’s Gallery at Buckingham Palace.
Martin Clayton, head of prints and drawings at the Royal Collection, said only one other portrait of da Vinci has survived from his lifetime.
The newly identified drawing is believed to be a more private glimpse of the Renaissance master, whose best-known work is the Mona Lisa.
It is believed that the two portraits were produced when da Vinci was about 65 years old – and the other contemporary image of the artist was by his pupil, Francesco Melzi.
Both show an “elegant straight nose”, a similar beard, and a “ringlet falling from the moustache at the corner of the mouth and long wavy hair”.
Upon examining both images, Mr Clayton said “it’s hard to avoid the conclusion that that is also an image of Leonardo”.
The face is on a sheet of paper which also contains the artist’s studies of a horse’s leg for an equestrian monument, commissioned by the French king.
Mr Clayton said: “Sheets of paper could be picked up in the studio and used by Leonardo’s assistants and companions just as rough paper for sketching on.”
It is thought that “one of Leonardo’s assistants picked up the sheet and made a couple of sketches… one of an old, bearded man.”
The expert said da Vinci was “renowned for his well-kept and luxuriant beard”, adding: “This very quick, casual sketch is the closest that we get of a snapshot of Leonardo during his own lifetime.”
Mr Clayton said Melzi’s portrait depicts da Vinci as “more thoughtful, more wistful, more troubled maybe” – as despite enjoying some of the most successful years of his life, “he knew he was dying”.
At the time, da Vinci could no longer paint because paralysis had struck his right arm.
“It’s incredible how much he did achieve but, by the goals he set himself, his career was something of a failure,” Mr Clayton said.
The Buckingham Palace exhibition will mark the 500th anniversary of the artist’s death and is the largest display of his work in more than 65 years.
Leonardo da Vinci: A Life In Drawing runs from 24 May to 13 October at the Queen’s Gallery, Buckingham Palace.