At the Royal College of Music Sumsion also met R. O. Morris, professor of counterpoint and composition. When Morris accepted a position at the Curtis Institute of Music in Philadelphia, he asked Sumsion to serve as his assistant; the two, along with Morris's wife Emmie, departed for America at the end of September 1926. The Curtis Institute was then a conservatory in its infancy, but figures such as Leopold Stokowski, famed conductor of the Philadelphia Orchestra, were associated with it in its early days. Sumsion's decision to accompany the Morrises was of consequence to his personal life as well as his career. Emmie Morris wrote frequently to her sister Adeline (who was married to Ralph Vaughan Williams) and reported 'with interest' on Sumsion's courtship of an American girl, Alice Garlichs. Sumsion had been introduced to Alice through her uncle, a professor at the University of Pennsylvania whom Sumsion had met on board the ship to America. On 7 June 1927, Herbert and Alice were married in Philadelphia.