She also wrote children's books and poetry, but may be best known for her Merlin series, which straddles the boundary between the historical novel and fantasy.

Adaptations of her books include both The Moon-Spinners: a Walt Disney live-action movie, and The Little Broomstick (1971) which became an animated feature film titled Mary and the Witch's Flower (2017, dir.

[1][2] She was a bright child and attended Eden Hall boarding school in Penrith, Cumbria, age eight.

[5] It was in Durham that she met and married her husband, Frederick Stewart, a young Scot who lectured in Geology.

Her novels are also known for their well-crafted settings, many in England but also in such locations as Damascus and the Greek islands, as well as Spain, France, Austria, etc.

Critically, her works are considered superior to those of other acclaimed romantic suspense novelists, such as Victoria Holt and Phyllis Whitney.

[10] In the late 1960s a new generation of young readers revived a readership in T. H. White's The Once and Future King (published in full 1958) and The Lord of the Rings (published in full 1956), and as a consequence Arthurian and heroic legends regained popularity among a critical mass of readers.

Mary Stewart added to this climate by publishing The Crystal Cave (1970), the first in what was to become The Merlin Trilogy, later extended by two further novels.

Mary Rainbow met and married her husband, Frederick Stewart, a young Scot lecturer in Geology, whilst they were both working at Durham University.