You’ll remember the supposed Leonardo “discovered” a few years ago and the fingerprint analysis that gave ballast to the theory. The vellum was also carbon dated to the potential period. The Telegraph‘s Richard Dorment dismantles the idea in detail:

Against all this, Kemp’s opponents point out that of the 4,000 or so surviving drawings by Leonardo, not a single one is on vellum. But vellum is a material a copyist might well use – because sizeable sheets of monastic vellum of the correct age are easy to come by, whereas blank sheets of paper made during Leonardo’s lifetime are not.

Nor does the observation that a left-handed artist drew the portrait convince the sceptics. According to Pietro C Marani, Italy’s most distinguished Leonardo scholar, who oversaw the restoration of The Last Supper : “The fact that one is looking at a drawing by a left-handed artist does not carry any weight: there exist copies of drawings by Leonardo made by imitators which present this particular characteristic – by, Francesco Melzi, for example, as Kenneth Clark and others have already written.” Likewise, a copyist could easily arrive at the sitter’s costume by studying any Milanese 15th-century portrait. Even the drawing’s obvious antiquity has drawn fire from one museum director, who asked not to be named. He believes the drawing is not even 19th century, and thinks it is “a screaming 20th-century fake”, made up out of a “compilation of obviously Leonardesque elements that is not even close to Leonardo himself”. For this well-known connoisseur of Italian painting and sculpture, the damage and repairs are suspicious, for, although apparent to the naked eye, they are not so extensive that they make the picture unappealing or unsaleable – as it would be, for example, if the repairs disfigured the face.

La Bella Principessa: a £1000m Leonardo, or a copy? (Telegraph)