He served as Chairman of the Joint Intelligence Committee during World War II and British Ambassador to Poland between 1945 and 1947.

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,[where?]

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.

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.

As chairman of the Joint Intelligence Committee, Victor Cavendish-Bentinck hesitated to believe Polish and Jewish information about atrocities.

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".

[citation needed] 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.

"[3] 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.