After graduation, Blackadder moved to London where she became a consultant in dermatology and
electro-therapeutics as well as working in radiology. She became a member of the
Royal College of Physicians of Ireland in 1904 and was appointed as a consultant for St. John's Hospital for Skin Diseases and the
South London Hospital for Women and Children. During World War I, Blackadder served as a radiologist at the Scottish Women's Hospital at Royaumont, France, returning to her position in London whenever there was a lull in the fighting. She used a state-of-the-art X-ray car which had been given to the hospital, and used this to understand and alleviate the effects of
gas gangrene through prompt diagnosis and treatment. While serving at Royaumont, Blackadder borrowed a
pianola from Paris and installed it at the hospital. She noticed that both patients and staff benefited from playing it and listening to it and she later wrote a book about the importance of music to well-being. The book,
Music, Health and Character, was published in 1923. It led to the establishment of the Council for Music in Hospitals. After the war, Blackadder returned to London and continued to practice medicine. She edited her husband's textbook, ''Savill's System of Clinical Medicine
, which she completed in 1942. She also became interested in ancient history and in 1955, she published Alexander the Great and his Times''. == Death and legacy ==