The Telegraph reports that an Italian family has come forward with a Leonardo da Vinci painting that has been kept in a Swiss vault. Previously only known as the subject of a sketch, the portrait of Isabella d’Este appears to prove that the artist completed the work. (Update: But Martin Kemp vigorously disputes this.) This is the third re-discovered Leonardo to come to light. What’s interesting about all three privately held works is that no transaction has yet been reported (Update: a quick responding reader says the reports of a sale of Salvator Mundi are credible):

Scientific tests suggest that the oil portrait is indeed the work of da Vinci, according to Carlo Pedretti, a professor emeritus of art history and an expert in Leonardo studies at the University of California, Los Angeles.

“There are no doubts that the portrait is the work of Leonardo,” Prof Pedretti, a recognised expert in authenticating disputed works by Da Vinci, told Corriere della Sera newspaper.

“I can immediately recognise Da Vinci’s handiwork, particularly in the woman’s face.”

Tests have shown that the type of pigment in the portrait was the same as that used by Leonardo and that the primer used to treat the canvas on which it was painted corresponds to that employed by the Renaissance genius.

Carbon dating, conducted by a mass spectrometry laboratory at the University of Arizona, has shown that there is a 95 per cent probability that the portrait was painted between 1460 and 1650.

But there needs to be further analysis to determine whether certain elements of the portrait — notably a golden tiara on the noblewoman’s head and a palm leaf held in her hand like a sceptre — were the work of Leonardo or one of his pupils, Prof Pedretti said.

Leonardo da Vinci painting lost for centuries found in Swiss bank vault (Telegraph)