Hillier was born in China but his family moved to England soon after his birth. He studied at Cambridge University for two years and was subsequently apprenticed to a firm of chartered accountants. However this career was quickly abandoned, when he decided to study at the Slade School of Fine Art from 1926. Until 1940 Hillier spent a great deal of time in France but retained strong links with London. In 1933 he joined the modernist group, 'Unit One'. Hillier developed his distinctive style in the mid-1930s, combining a precise style of painting with a sense of stillness evoking the strangeness of Surrealism.