In her book ‘The Secret Lives of Colour’ the author Kasia St Clair expands upon the social roots, cultural understanding and history of a range of colours. Blue, being one of my favourite colours, gets special treatment; first listing the shades of the colour, she then uses a range of evocative descriptors to alert us to the wonder of this colour; Ultramarine, Cobalt, Indigo, Prussian Blue, Egyptian Blue, Woad, Electric Blue, Cerulean.