The smartly dressed man with frown lines and a bristling moustache is as much a mystery as the rollicking scene in Vulcan's forge, where a cherub is in imminent danger of being clouted by the blacksmith's hammer. They are among thousands of enigmatic paintings, hanging in galleries, council chambers, boardrooms and fire stations, about which almost nothing is known.

The public, however, is being invited to turn art detective, and help trace artists, dates, subjects and other helpful information about the paintings.