Philip W. Errington is a renowned expert in antiquarian books and manuscripts, with a 35-year career at Sotheby's London, where he served as a director and specialist in 20th-century printed books and manuscripts. He is the author of "John Masefield: The Thames and the Thames Estuary" (2014) and "J.R.R. Tolkien: A Descriptive Bibliography" (2017), considered the definitive Tolkien bibliography. He has also contributed articles to journals such as The Book Collector, Transactions of the Cambridge Bibliographical Society, and Tolkien Studies. He is a member of The London Library and The Bibliographical Society.