David Crouch is professor of medieval history at the University of Hull. He is an aurthority on twelfth-and thirteenth-century English and Norman history. His works on aristocracy include: "The Beaumont Twins" (Cambridge, 1986); "The Image of Aristocracy in ""Britain,"" 1000-1300" (Routledge); "William Marshal" (2nd edn, Longman). He has also published "The Reign of King Stephen, 1135-1154" (Longman) and "The Normans: the History of a Dynasty" (Hambledon).