The small picture of a young woman in profile was previously believed to be a German work from the early 19th century and has changed hands in recent years for around £12,000.
But a growing number of leading Leonardo scholars agree the work is almost certainly by the Renaissance figurehead because it appears to have his fingerprint on it. Carbon dating and infrared analysis of Leonardo’s techniques back up the theory.
If the scholars are correct, it will be the first major work by Leonardo to be identified for 100 years and will be worth tens of millions of pounds.
Martin Kemp, emeritus professor of the history of art at Oxford University, is so convinced the portrait is a Leonardo that he has written an as yet unpublished 200-page book about it.
The fingerprint, which corresponds to the tip of the index or middle finger, was found by Peter Paul Biro, a Montreal-based forensic art expert, when he examined images taken of the portrait by the revolutionary multispectral camera.
Biro believed the fingerprint, which was found near the top left corner of the work, was “highly comparable” to a fingerprint on Leonardo’s St Jerome in the Vatican, the Antiques Trade Gazette reported.
Drawn in ink and chalks, the beautiful young woman’s costume and elaborate hairstyle reflected Milanese fashion of the late 15th century, and carbon analysis was consistent with that dating.
Kemp believed that “by a process of elimination”, the fresh-faced teenager could be Bianca Sforza, the daughter of Ludovico Sforza, Duke of Milan from 1452-1508, and his mistress Bernardina de Corradis.
He said he thought the portrait, which measures 33cm x 22cm, must date from around 1496 when, aged 13 or 14, the Bella Principessa married the Duke’s army captain, Galeazzo Sanseverino, a patron of Leonardo’s. She died four months after the wedding.