The author and illustrator of such children's books as Baker Cat, Bouncing Buffalo, Tamara Drewe, and Gemma Bovery, she also worked as a newspaper cartoonist. In 1977 she began publishing The Silent Three of St. Botolph's, a popular comic strip that appeared in The Guardian. She studied at both the Sorbonne in Paris and the Central School of Art & Design in London. She published her first children's book, The Posy Simmonds Bear Book, in 1969.