Malcolm Lambert was formerly Reader in Medieval History at the University of Bristol. Of his book Medieval Heresy (now in its third edition), the American medieval historian, Norman F. Cantor, wrote: 'A masterpiece of learning, thought, and insight. No serious student of the Middle Ages will fail to read and indeed reread this seminal work. I regard it as one of the finest and most important books on medieval history ever written.' His other books include The Cathars (1998) and Christians and Pagans: The Conversion of Britain from Alban to Bede (2000). He lives in Worthing.