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. However, he cast doubt on reports that were received regarding the Nazi genocide of the Jews. In late August 1943 the Polish Embassy in London informed the British government of the deportation and annihilation of hundreds of thousands of Jews from Lublin and Bialystok provinces. The chairman of the Joint Intelligence Committee, Victor Cavendish-Bentinck, deplored Polish and Jewish information about atrocities. He wrote this information as an attempt to ‘stoke us up’ He added: ‘I feel certain that we are making a mistake in giving credence to this gas chamber story.’ In 1945, Cavendish-Bentinck was given his final diplomatic posting on his appointment as Ambassador to Poland. When visiting the formerly German City of Stettin in 1946 he was invited to talk to German civilians suffering from months of internment so their possessions and property could be taken over by Polish resettlers from territories lost to the USSR. Cavendish-Bentinck refused to do so, ignoring certain inhuman circumstances under which mainly old people, women and children had to suffer, by noting to his Polish hosts, he was "convinced that they will complain as usual". He held the position for two years before the Foreign Office applied to appoint him Ambassador to Brazil. He never took up the latter post, being obliged to resign from the Foreign Office, without a pension, as a result of the publicity surrounding his divorce. Bentinck's aristocratic background attracted press attention; Foreign Secretary Ernest Bevin, apparently sympathetic, remarked at that the time "I could have saved him if his name had been Smith."
Later life and Duke of Portland
After his withdrawal from the diplomatic service, Cavendish-Bentinck embarked on a business career, becoming Vice-Chairman of the Committee of Industrial Interests in Germany. From this position, he was able to advance the interests of British companies such as Unilever. He was a member of the Steering Committee of the Bilderberg Group. In 1980 he succeeded his elder brother Ferdinand Cavendish-Bentinck as the 9th Duke of Portland. Upon his own death in 1990, the dukedom and the Marquessate of Titchfield became extinct because his only son had predeceased him and there were no other surviving male heirs of the 1st Duke. However, the earldom of Portland had been created in an earlier generation than the dukedom and there were surviving descendants in the male line to inherit it. That title was therefore inherited by his kinsman, Henry Noel Bentinck, who became 11th Earl of Portland, together with its subsidiary titles of Viscount Woodstock and Baron Cirencester. He was interred at the traditional burial place of the Dukes of Portland in the churchyard of St Winifred's Church at Holbeck.
Marriages and children
Bentick married Clothilde Bruce Quigley, an American, on 16 February 1924. She was the daughter of James Bruce Quigley. They had two children together:
Soon after World War II began Bentinck received a telephone call at his office from his Hungarian maid to tell him that his wife had left him and taken their children with her. They were finally divorced in 1948. Portland married secondly, Kathleen Elsie Barry on 27 July 1948. She was the daughter of Arthur Barry. This marriage produced one child:
