At the outbreak of World War II, Clarke was in the US visiting her two brothers, and was unable to obtain a visa to return to Britain. She lived for a while with her brothers' families and then in 1942 took a position as a governess for a family in Connecticut. She composed 10 works between 1939 and 1942, including her "Passacaglia on an Old English Tune". She had first met James Friskin, a composer, concert pianist, and founding member of the Juilliard School faculty, and later to become her husband, when they were both students at the Royal College of Music. They renewed their friendship after a chance meeting on a Manhattan street in 1944 and married in September of that year when both were in their late 50s. According to musicologist Liane Curtis, Friskin was "a man who gave a sense of deep satisfaction and equilibrium."