Born the son of Major Lord Bernard Gordon-Lennox, Gordon-Lennox joined the Royal Navy in 1924. He served in the Middle East, in East Coast convoys and in Arctic convoys during the Second World War. He became Commanding Officer of the sloop HMS "Mermaid" as well as Captain of the 2nd Frigate Squadron in 1954. He went on to become Commander of the signal school HMS "Mercury" in 1955, Flag Captain commanding the cruiser HMS "Newcastle" during the Malayan Emergency in 1957 and Deputy Chief of Supplies and Transport at the Admiralty in 1959.