Josephine Barnes was born in Norfolk, the eldest child of a Methodist minister and a professional musician. The family moved around the country, and she spent much time at vicarages in Yorkshire and Oxford. She decided to become a doctor at the age of 13. She studied physiology at Oxford University and then obtained her medical training at University College Hospital (UCH) in London. It was here that she decided to specialize in obstetrics and gynecology and became one of the few female surgeons of her day. In 1942, she married Brian Warren, a fellow physician, with whom she had three children before they divorced. At the start of World War II, she was named to a post at the Samaritan Hospital. After holding various junior appointments, Dr. Barnes was appointed deputy head of the Obstetric Unit at UCH in 1947. She also served for two decades (1947–1967) as the resident surgeon at the Marie Curie Hospital. Early in her career, Dr. Barnes made house calls to deliver the babies of poor women, and she devoted her life to improving the health and welfare of British mothers and babies. Dr. Barnes served as the first female president of the British Medical Association in 1979, and was closely associated with the National Association of Family Planning Doctors. Her concern about infant mortality led her to chair the steering committees of two state maternity surveys between 1948 and 1970, which followed babies through their lives in an effort to measure the impact of their premature birth on their later development. She was appointed a Dame Commander of the British Empire in 1974 for her contributions to medicine.