 Medley was born in London, one of six children to Charles Medley, a highly successful copyright lawyer who was friends with many writers of the day.He was educated at Gresham's School in Holt, Norfolk from 1919 to 1923, before briefly attending the Byam Shaw School of Art.During 1924 Medley studied art at the Royal Academy Schools but soon switched to the Slade School of Fine Art and then completed his art training by spending two years, from 1926 to 1928, in Paris.