A decorated officer during the Second World War, he later entered politics, serving as a Liberal Party member of the New South Wales Legislative Assembly from 1957 to 1964, representing the electorate of Vaucluse.
Rising to the rank of sergeant by 1939, Cox was commissioned as a lieutenant later that year and enlisted in the Second Australian Imperial Force for active service in the Second World War.
He was a platoon commander in the Middle East and Greece in the early stages of the war, where he met his later wife, whom he married during a brief return to Australia in 1942.
Cox was later promoted to major and lieutenant colonel, and was awarded the Distinguished Service Order for his role in administering two successful operations in 1945, during the closing stages of the war.
Cox returned to Bondi after the war, working as a real-estate agent in the family business, and remaining active in the Citizens Military Force, where he rose to the rank of brigadier.