Sargent worked first as an organist at St Mary's Church, Melton Mowbray, Leicestershire, from 1914 to 1924, except for eight months in 1918 when he served as a private in the Durham Light Infantry during the First World War. He was chosen for the organist post over more than 150 other applicants. In addition to his organ playing he worked on many musical projects in Leicester, Melton Mowbray and Stamford, where he not only conducted but also produced the operas of Gilbert and Sullivan and others for amateur societies. The Prince of Wales and his entourage often hunted in Leicestershire and watched the annual Gilbert and Sullivan productions there, together with the Duke of York and other members of the Royal Family. At the age of 24 Sargent became England's youngest Doctor of Music, with a degree from Durham.