Dilley studied the colonial politics of East Africa, particularly British colonialism in Kenya. In 1937, Dilley published her PhD dissertation thesis in the form of a book, also called British policy in Kenya Colony.[5] The book was republished in 1966.[6] British policy in Kenya Colony described the policy of the British Empire towards Kenya during the period in which Kenya was a colony of Britain, and largely focused on the personalities and behaviors of British settlers in Kenya.[6] For this reason, the book was praised for being one of the first analyses to turn a critical eye towards British colonial activity in East Africa, and was viewed by the Colonial Office as highly critical of their policies,[1] but was also critiqued for eliding and largely omitting the actions and preferences of the Kenyan people.[6] The fact that she wrote the book in England and America without ever visiting Kenya was described both as a benefit and a detriment, leading to a deeply researched volume that also lacked any detailed discussion of the victims of colonization.[7] The book was also particularly noted for making substantial evidence available from the library of the Colonial Office when direct evidence of Britain's colonial activities was lacking, particularly in America.[1][6]
During World War II, Dilley worked on welfare and relief efforts for the children of Bristol, England, for which she was awarded the King's Medal for Service in the Cause of Freedom by King George VI.[1] Dilley died on October 28, 1989.[1]