Kathleen Grace Norton was born in Kennington, London, in May 1899, into an old medical family: like her grandfather, her father was a GP, and her mother had trained as a nurse, although she never qualified. She had an elder sister, who in future years stayed at home to look after her parents, and three younger brothers.

From the age of eight Kathleen wanted to be a doctor, but her father was opposed to the idea until he witnessed the competent role women played in the First World War. He relented and in 1918 allowed his daughter to go to St Hughs College, Oxford, to read medicine as a pioneer woman student: “There wasnt a medical book in the library” While she was at Oxford she took part in various experimental medical research projects, such as the use of the first electro-cardiogram and studies of the effect of lack of oxygen on the body. After graduation, Kathleen went on to St Marys Hospital, Paddington, following ber father's path, and then when she qualified in 1925 she joined his practice in Kennington. When he died, slowly, of tuberculosis, she continued working from the same surgery.