Question: Who was the author of the book, on which Channel 4's 1982 film, for which Howard Blake wrote the soundtrack. is based ? 
Sentence (from "The Snowman"): The Snowman is a children's picture book without words by English author Raymond Briggs, first published in 1978 by Hamish Hamilton in the United Kingdom, and published by Random House in the United States in November of the same year.
Relevant evidence: Yes