Clarke sold the Stradivarius she had been bequeathed, and established the May Mukle prize at the Royal Academy. The prize is still awarded annually to an outstanding cellist. After her husband's death in 1967, Clarke began writing a memoir, entitled "I Had a Father Too (or the Mustard Spoon)"; it was completed in 1973 but never published. In it she describes her early life, marked by frequent beatings from her father and strained family relations which affected her perceptions of her proper place in life. Clarke died in 1979 at her home in New York City at the age of 93, and was cremated.