Art secrets laid bare at exhibition

Close Examination – Fakes, Mistakes and Discoveries demonstrates the results of investigation by scientists, art historians and conservators. Portraits include Woman at a Window, above, a 16th-century painting of what appeared to be an innocent, demure Victorian beauty.

It was later discovered that the woman had originally been painted as a sultry blonde seductress who was toned down for prudish Victorians.

Other paintings on display include Raphael's The Madonna of the Pinks, long thought to be a fake until scientists found subtle differences between the underdrawing and the finished painting that proved it was genuine. The gallery's own errors are on show with a painting thought to be a Botticelli bought by the gallery in 1874 which turned out not to be by the famed artist.