Atherton began his career as a film and television armorer at the age of 16 when he took up an apprenticeship with a gunsmith in Cornwall, England. His first job in the entertainment industry was on the British/Belgian World War II television series Secret Army, which ran from 1977-1979. He later joined weapons prop house Bapty & Co., working on such high-profile productions as Indiana Jones and the Raiders of the Lost Ark, Aliens (where he was the principle designer and builder of the practical M41A Pulse Rifle props, working to conceptual designs by director James Cameron), Alien3 (where he built the backpacks worn by the Weyland-Yutani Commandos) and Judge Dredd (where he built the Judges' Lawgiver handgun).