	In 1765 he received his MD and established a medical practice in Birmingham, and shared a house with the physician John Ash who was the chief campaigner for the Birmingham infirmary. Small was Boulton's physician and became a close friend of Erasmus Darwin, Thomas Day, James Keir, James Watt, Anna Seward and others connected with the Lunar Society. He was one of the best-liked members of the society and an active contributor to their debates.