 According to an interview with Euan Lloyd in "Cinema Retro" magazine, producer and star Widmark had disagreements with Karlson, who felt he should use a tongue-in-cheek approach for the story.Perhaps because one of the screenwriters was Widmark's wife, Jean Hazelwood, Widmark took over directing the film.Lee Child thought the novel was MacLean's best and said it was influential on Child's own writing, saying "Looking back on it, it was a rather hysterical Cold War novel, but it had some of the best-drawn characters I had read in the genre...