Sir Kenneth Clark was arguably the most influential figure in 20th-century British art. Born into a world of privilege, his achievements were staggering. He keeper of the King's Pictures, director of the National Gallery, founder of the Arts Council and independent television, and best remembered as the presenter of the most ambitious arts series ever made - Civilisation. A staunch defender of Reithian values, Clark was attacked for being an elitist 'posh man in tweeds'. But he held a passionate belief that art was for everyone and made it his mission, through television, to share his love of art with the masses. To coincide with Tate Britain's exhibition on Clark opening in May, this Culture Show special presents an intimate portrait of a contradictory and elusive character who transformed our cultural landscape.