Question: Who is the author of the book that has a musical adaption in which "Over the Rainbow" series in the United Kingdom was auditioning aspiring musical theatre performers for a role?
Sentence (from "Jennifer Gillis"): Since "Over the Rainbow", Gillis sang the Canadian national anthem "O Canada" for the Prime Minister of Canada, Stephen Harper on Parliament Hill in Ottawa, Ontario on Canada Day in 2013.
Relevant evidence: No