After 18 years working at the National Portrait Gallery, art historian Sir David Piper served as its director from 1964 until 1967. He was later a director at the Fitzwilliam Museum in Cambridge and the Ashmolean Museum in Oxford. His books include The English Face and The Companion Guide to London. He wrote novels using the name Peter Towry, most notably Trial by Battle (1959), which was based on his experiences as a prisoner of the Japanese during World War II. He died in 1990, aged 72.