Fouldes and the illustrator Raymond Briggs collaborated on a picture book for young children, "The Elephant and the Bad Baby", published by Hamish Hamilton in 1969. Probably it is her most famous work; by a wide margin, as it is the one most widely held in WorldCat participating libraries. It features a baby who refuses to say please and goes romping through town on the back of an elephant while being chased by various townspeople. "The Elephant and the Bad Baby" is a "cumulative story" with a "poetic feel", a common effect drawn from the picture-book format of the text.