Mary Coate was the daughter of clergyman Harry Coate, and his wife Henrietta,
née Nihill. Her younger sister was missionary headmistress
Winifred Coate. She gained an MA from
St Hilda's College, Oxford, and was one of the
first women admitted to degrees at Oxford when this became possible in 1920. She taught history at
Lady Margaret Hall, Oxford from 1918 to 1947, being elected Fellow there in 1922. In 1933 she produced her most notable work,
Cornwall in the Great Civil War and Interregnum. She supported the Association of Friends of the French Volunteers (AVF) in
World War II, corresponding with members of the
French Resistance. Élisabeth de Gaulle, daughter of
Charles de Gaulle, was one of her students. In 1947 she conducted fieldwork in Spain researching the
Conde de Gondomar. She was a Fellow of the
Society of Antiquaries and a Fellow of the
Royal Historical Society. == Widening participation at Oxford ==