Fiona and Philip attempt to help a man who believes he owns a painting by French post-impressionist Edouard Vuillard.

Fiona and Philip attempt to prove that two paintings are missing works by one of the country's best-loved artists, John Constable.

Fiona and Philip attempt to help Martin Lang try and prove the painting he bought in 1992 is by modern master Marc Chagall.

This week the focus is on Britain's public art collections, in which 17,000 paintings are listed as `artist unknown'. Philip identify several works they believe are by Thomas Gainsborough.