“The Tate launches a major campaign today to purchase one of Turner’s late masterpieces, The Blue Rigi, a heartstopping view of Mount Rigi seen from Lake Lucerne in Switzerland, in which he captured the elusive moment when night fades into the pale light of dawn. The work is, according to the Tate, one of the finest watercolours painted. It needs to be, for Tate Britain must raise £4.95m to prevent it leaving the country. This would be the biggest sum it has ever paid for a single work of art.”