Beginning in 1961, Serraillier devoted most of his time to writing fiction and non-fiction, poems, and educational programmes for television. He also produced retellings of classic and ancient legends for children, in prose and verse, including "Beowulf", works by Chaucer, English folklore, and Greek and Roman myths. In 1948, together with his wife, Anne Margaret Rogers, he founded the New Windmill Series. Published by Heinemann Educational Books, the series set out to provide inexpensive editions of good stories, including fiction, travel and biography for older readers. He continued as co-editor of the series until the onset of Alzheimer's disease in the early 1990s.