Mary Stewart was born Mary Florence Elinor Rainbow on September 17, 1916, in Sunderland, County Durham, England. Her father, Frederick A. Rainbow, was a clergyman, and her mother, Mary Edith Rainbow, came from a family of New Zealand missionaries. Stewart was one of three children. When she was seven, the family moved to the mining village of Shotton Colliery in County Durham, and Stewart attended a number of different schools before going to Durham University in 1935. At university, she became president of the Women’s Union and of the Literary Society; she was graduated in 1938 with a first-class honors degree in English.
In 1939, she received a diploma in the theory and practice of teaching. She then taught at a school in Middlesborough, in northern England, before becoming head of English and classics at Worcester School, in the Midlands. In 1941, she received an master of arts degree from Durham University and was appointed assistant lecturer in English; during the last years of World War II, she served part-time in the Royal Observer Corps.
In 1945, Stewart married Frederick Henry Stewart, who at the time was a lecturer in geology at Durham University. From 1948 until 1956, she continued her work as lecturer at the university, but on a part-time basis, and she also taught at St. Hild’s Teacher Training College in Durham. In 1956, she gave up teaching to concentrate on her writing. She had been writing stories and poems since she was a child, and during her teaching career her poems had been published in the Durham University Journal. She started her first novel with no thought of publication, but her husband persuaded her to submit the manuscript to a publisher. Madam, Will You Talk? was published in 1955, and Stewart’s literary career had begun. The Stewarts then moved from Durham to Edinburgh, where Frederick Stewart had been appointed professor of geology at the university. Between 1955 and 1984, Stewart published nineteen novels, including three for children. In 1960 she was the runner-up for the Crime Writers’ Association’s Gold Dagger Award. She received the Malice Domestic Award for Lifetime Achievement in 1996.