Is this painting of a Roman emperor a lost Leonardo da Vinci?

Chemical analysis of a painting of the Roman emperor Domitian has thrown light on the mystery of who painted it. Interest in its provenance dates back to the discovery, hidden below Domitian’s right arm in a blackened area, of these words: L da Vinci. Pinxt.

Could it be an unknown Leonardo da Vinci painting? This is what two siblings, the owners of the painting who wish to remain anonymous, have wondered for over 30 years. When they inherited the Domitian in 1994, they chanced upon the faint inscription beneath centuries of soot. ‘At first there was a certain sense of excitement – almost of celebration,’ they explain. ‘We were naive enough to imagine that the question might be resolved relatively quickly, perhaps within a few months.’