He attended Westminster School and then read classics at Trinity College, Cambridge where he was a contemporary of Leonard Woolf, Thoby Stephen and Clive Bell.
[1] In 1917 he joined in a scheme to purchase The Mill House, Tidmarsh, the place lived in by Lytton Strachey, Dora Carrington and Ralph Partridge and which he occasionally visited.
He fell in love with the artist Barbara Hiles, a friend of Dora Carrington, but, when she decided to marry Nick Bagenal,[note 2] Sydney-Turner refused her offer to stay as her lover.
He was a kind and unambitious person whose friend Leonard Woolf described him as "an eccentric in the best English tradition who wrote elegant verse and music and possessed an extraordinary supple, and enigmatic mind".
He lived for over thirty years in a furnished apartment in Great Ormond Street with a large sitting room and a very small bedroom where he kept a stack of "good pictures" by Duncan Grant and other artists.