I now learn that one of these, Saskia Carrying Rumbartus Downstairs, a pen-and-ink sketch after Rembrandt's original in the Pierpont Morgan Library in New York, has recently been stolen, together with silver items, from a Suffolk house.
The owner is the father-in-law of well-known picture dealer Jonathan Dodd of Waterhouse & Dodd in London's Cork Street, who believes there are no labels on the frame to indicate that the work is fraudulent.
While not demeaning the seriousness of the burglary, Mr Dodd does think it quite amusing. As he explains: "Somewhere, sometime, the thieves will be trying to dispose of what looks like a very good Rembrandt drawing. However, the buyer who suspects it's the genuine thing will have two major disappointments: first it's not, and second it's hot. And having sold a drawing as a quite acknowledged fake, I think Hebborn will be laughing in his grave."
The picture, which is illustrated as Plate 21 in Hebborn's The Art Forger's Handbook (published in 1997 by Cassell), shows a woman carrying a child down a narrow flight of stairs. Anybody with information on the drawing's whereabouts should telephone the Suffolk Constabulary on 01473 613500.
