Painter and teacher, born in Beaconsfield, Buckinghamshire, son of the artist Maurice Codner, father of the painter Stephen Codner. He studied at Regent Street Polytechnic School of Art under Harry Watson, 1930–2. Taught at Sir John Cass School of Art, 1947–51. Codner showed at RWA of which he was a member from 1947, also at RA and RP. Had solo shows in London and the west of England, RWA holding his work. Until the death of his father in 1958 Codner signed pictures John Whitlock, thereafter John Codner. Lived in Stokenham, Devon.