Margery Jean Gill was born in Coatbridge, Scotland, on April 5, 1925. She illustrated many children's books from 1954 onwards, until at least 1977. Gill studied at the Harrow School of Art and took etching and engraving courses at the Royal College of Art, London. Gill's work is mainly black and white line drawings. The only Susan Cooper title that Margery Gill illustrated was the first UK edition of Over Sea, Under Stone, for which she produced a two-colour dustwrapper, full page black and white frontispiece, 11 other full-page B&W drawings and four double-page spread b&w drawings.