Premise: William Mercer Cook (January 27, 1869 – July 19, 1944), better known as Will Marion Cook, was an African-American composer and violinist from the United States. Cook was a student of Antonín Dvořák and performed for King George V among others. He is probably best known for his popular songs and Broadway musicals, such as "" and "In Dahomey".
Hypothesis: William Mercer Cook performed for King George more than once.