It immediately sold out but disappeared until re-issued in abridged form by Kaye Webb at Puffin Books twenty years later, when it became a best-seller.
Both were enthusiastic Girl Guides, attending some of the movement's first camps, and some of Ursula's early books were collections of stories she had told to her own Brownie pack.
Thanks to their uncle, the publisher Stanley Unwin, the twins visited the Alps, which later inspired some of Ursula's most vivid writing, most notably the trilogy that began with The Three Toymakers.
Events from her childhood recur repeatedly in her fiction, with North Stoneham described at greatest length in the 1941 A Castle for John-Peter and depicted in Faith Jaques' illustrations for Grandpapa's Folly and the Woodworm-Bookworm of 1974.
Much of her later writing included disruptive, but essentially good-hearted children, and was influenced by her work as a juvenile magistrate and as a highly involved school governor.