McRobbie came from a poor family of five children who were evacuated during World War II down the Scottish coast to Ayr. In 1958, McRobbie moved to Australia and worked as an apprentice marine fitter and a ship's engineer. He trained as a primary-school teacher in Papua New Guinea and worked as a college lecturer and parliamentary researcher there.
McRobbie is also a scriptwriter and producer of children's radio and television programs for the Australian Broadcasting Commission. He wrote the scripts for the successful television series The Wayne Manifesto based on his series of books about twelve-year-old Wayne Wilson. McRobbie also wrote for reading schemes and contributed material on creative writing for schools. He is a full-time writer and lives in Brisbane, Queensland.