Dr K S B Keats-Rohan is Director of the Linacre Unit for Prosopographical Research and Fellow of the European Humanities Research Centre, University of Oxford. Daniel Power is Professor of Medieval History at Swansea University. He is the author of a number of works concerning France and the British Isles in the Central Middle Ages, including The Norman Frontier in the Twelfth and Early Thirteenth Centuries (2004). He is a Fellow of the Society of Antiquaries (of London) and of the Royal Historical Society. Elisabeth van Houts is Honorary Professor of European Medieval History, University of Cambridge, and Fellow of Emmanuel College. Dr K S B Keats-Rohan is Director of the Linacre Unit for Prosopographical Research and Fellow of the European Humanities Research Centre, University of Oxford.