'The Secret Lives of Colour' tells the unusual stories of the 75 most fascinating shades, dyes and hues. From blonde to ginger, the brown that changed the way battles were fought to the white that protected against the plague, Picasso's blue period to the charcoal on the cave walls at Lascaux, acid yellow to kelly green, and from scarlet women to imperial purple, these surprising stories run like a bright thread throughout history.