Born in Orange, New Jersey where her Canadian father (Alfred Orde Tate) was engaged in electrical research; he was Thomas Edison's secretary. Her mother (Eliza H. "Bessie" Dean) was the daughter of Hon. William W. Dean, County Court Judge of Victoria, Ontario.
Dorothy went to a private girls' school in Toronto and then to the Sorbonne. She published her first novel, The Story of Yuku (1910) in Toronto when she was seventeen, but did not publish again until 1928. Her lifetime output amounted to more than fifty books, many issued under multiple titles.
She married Leland B Duer in Ongar, Essex in July 1913 and married Edgar Willoughby Duffield in London's St Martin's in 1921. Duer was a lawyer who went on to be the senior partner of the New York law firm of Duer & Taylor. Edgar Duffield gave his occupation as fireeater when the couple visited Canada in 1928 but he had been an Army intelligence officer in the First World War and received the OBE for his services. In 1929 they visited New York. The couple lived in Aldbourne, Wiltshire, until Edgar's death in 1965. She stayed there as a widow until her death in 1976.
Westcountry Studies Library in Exeter, Devon, holds a notebook, draft of romantic novel, diary, autobiographical notes, photos, typewritten MS of novel, “Magnificent Emily”, and four other stories.