“There isn’t a major gallery in the world that doesn’t house – and in most cases proudly display – works that “aren’t what they seem”. There is a joke among art dealers and forgery specialists that of the 324 canvases (or whatever the precise figure) painted by Corot, 562 are hanging in museums and private houses in America. The former Met director Thomas Hoving reckoned 40 per cent of the works offered to the museum were either phonies or so hypocritically restored they were no better than forgeries.”