cavendish-bentinck did not pursue a university education, instead entering the diplomatic service in 1915 at the age of 18 before taking leave to fight with the grenadier guards in the first world war, returning to the foreign office in 1919. in 1922, he took charge of administrative arrangements for the lausanne conference. he served in the british embassy in paris and also in the league of nations department in the foreign office. other postings included athens in 1932 and santiago in 1933. the high point of his diplomatic career came in 1939 when he was appointed chairman of the joint intelligence committee. he managed to develop the body as a highly effective instrument of government and, as a result, became counsellor to the services liaison department of the foreign office in 1942.