Stewart McAllister was born in Wishaw, Lanarkshire, Scotland, as the only son and second surviving child of Hugh and Jeanie McAllister. He had a comfortable childhood with his three sisters, and his father's membership in the local photographic club sparked his interest in experimenting with film. This curiosity would later manifest in his decision to build a television from scratch, as well as his fascination with photography.
McAllister attended Wishaw High School before pursuing his passion for painting at the prestigious Glasgow School of Art. He graduated in 1936, winning the Dame Laura Knight travelling scholarship for his outstanding portrait painting. Despite the increasingly tumultuous political climate, he embarked on a grand tour, visiting major capitals as far east as Hungary, armed with letters of introduction for each country.
McAllister's photographic memory proved to be a valuable asset, and he was later recruited by MI6 to interpret aerial spy photographs during World War II. During his time at Glasgow Art School, he collaborated with Norman McLaren, experimenting with hand-drawn sound tracks on film animation, a technique that McLaren would later employ in his early work in Canada.
In London, McAllister worked with John Grierson, directing, producing, and editing films for the Crown and GPO film units. Despite his shy and modest nature, his dedication to his craft left little time for personal relationships. However, in the final year of his life, he developed a close bond with colleague Eireanne Sturdie, and it seemed likely that they might have married.
Tragically, McAllister's life was cut short when he became ill, and he returned to Scotland, where he was nursed first at home and then in the hospital's "Sick Bay." He passed away at the end of 1962, leaving behind a legacy of artistic and creative achievements.
