In 1981, Simmonds was named Cartoonist of the Year in the British Press Awards. In 1982 and 1983 she contributed a regular full-page strip to Harper's Magazine in America. In 1987 Simmonds turned her hand to writing, as well as illustrating, children's books. Fred, the story of a cat with a secret life, was later filmed as Famous Fred and nominated for the Academy Award for Animated Short Film and several BAFTAs. Her other children's books include Lulu and the Flying Babies, The Chocolate Wedding and Lavender.
