In 1920 Campbell returned to Guy's Hospital as a medical registrar. He graduated DM in 1921 and qualified MRCP in 1921. He spent three years (from 1923 to 1925) in the department of physiology working with E. P. Poulton on oxygen therapy[3] and with Marcus Pembrey. Campbell held from 1923 to 1927 a Beit memorial research fellowship, in 1925 resumed clinical work as a medical registrar, and in 1926 became an assistant physician at Guy's Hospital.[3] He was elected FRCP in 1929.[2]
His early publications included papers on respiratory and gastric physiology, paroxysmal atrial rhythm disturbances, complete heart block, the use of quinidine, the heart in thyroid disease, and the effects of exercise on the heart and digestion.[1]
At the National Heart Hospital he began working in 1926 with the cardiologist John Parkinson and in 1930 became there a consultant physician.[3] During WWII Campbell was superintendent of the Emergency Medical Service Hospital, Orpington. At Guy's Hospital he was promoted in 1945 to general physician, and in 1948 became a cardiologist and head of the newly-founded cardiac department.[1]
In 1938, he became the first editor of the British Heart Journal (along with Evan Bedford) which he continued to edit for 20 years until 1958.[1]
This led to an intense period of surgical development and close collaboration with Russell Brock and Charles Baker that would make Guy's Hospital famous for its surgery on congenital heart disease and mitral stenosis.[1]
Campbell published in 1935 a book entitled Sherlock Holmes and Doctor Watson: A Medical Digression and was an active member of the Sherlock Holmes Society of London.[2] In the autumn of 1972 he made a lecture tour of American medical centres.[3]
J. Maurice Campbell's father was the mathematician John Edward Campbell. On 28 August 1924 in Nefyn, Caernarfonshire, Maurice Campbell married Ethel Mary Chrimes, a nurse at Guy's Hospital. He was survived by his widow, two sons and three daughters.[2]
