He served as the Chairman of the Arts Council of Great Britain and the South Bank Theatre Board.

John Fremantle was born at Holton Park, Oxfordshire, on 2 March 1900.

He was a Conservative Party member of the London County Council representing Hampstead from 1945 until 1955.

He was a Deputy Lieutenant of London from 1951 to 1976 and was invested as a Knight Grand Cross, Order of the British Empire (G.B.E.)

He married, secondly, Gloria Jean Irene Dunn,[5] daughter of W. E. Hill, on 26 March 1959.