When she started work at CBC radio in 1939, Mary Grannan was responsible for two weekly children's programs. "Just Mary", which was heard from noon to 12:15 on Sundays, was intended for children from four to eight years old. "The Children's Scrapbook", a half-hour program directed at older school-aged children, was broadcast on Saturday afternoons beginning at 12:30. It offered a variety of content, including plays, interviews, and documentary broadcasts recorded outside the studio in places such as a zoo or a newspaper's linotype printing operation. The reporter for these documentary segments was Austin Willis, who was the regular announcer on both of Mary Grannan's programs. From fall 1945 to spring of 1946, an evening edition of "The Children's Scrapbook", called "Evening Scrapbook", appeared on Thursday evenings. "The Children's Scrapbook" ceased production in the spring of 1946. To replace it, Mary Grannan wrote and produced a new half-hour program called "The Land of Supposing". The program, which presented dramatizations of original stories by Mary Grannan, as well as adaptations of fairy tales and folk tales, ran from April through June from 1946 to 1948, and again in 1950. The "Maggie Muggins" radio program was first broadcast on 1 January 1948 and was heard on Wednesday afternoons. It was based on Mary Grannan's book, also entitled "Maggie Muggins", which had been published in 1944. Unlike the "Just Mary" stories, "Maggie Muggins" had a continuing cast of characters. By 1949, it had a larger audience than any other Canadian children's program. The radio series ended in June 1953, when the actress who played Maggie graduated from high school. "Maggie Muggins" became a television program in February 1955. In 1960 Mary Grannan retired, having reached the age of 60, the mandatory retirement age for women at the Canadian Broadcasting Corporation. She stayed in Toronto and continued to work on her two programs, "Just Mary" on radio and "Maggie Muggins" on television, as a freelancer. In April 1962 a new supervisor of children's programming was appointed and both programs were cancelled. Mary Grannan returned to Fredericton and spent the rest of her life there, dying in 1975 of heart failure. The family home, where she lived with her two sisters after retirement, was recognized as a New Brunswick Historic Site in 1999.