The portrait of Reverend Robert Walker by Sir Henry Raeburn is world famous. On permanent show in the National Gallery of Scotland, the black-clad minister, skating enigmatically over Edinburgh's Duddingston Loch on a wintry afternoon, is a now familiar icon of Scottish culture. The painting gained new fame recently as an inspiration to the architect of the new Scottish Parliament building. Read about the Edinburgh Enlightenment times of artist and sitter and how the painting - virtually unknown until 1942 - has become so loved.