In the Middle Ages, Prester John was seen as the great hope for Crusaders struggling to hold on to, then regain, Jerusalem. He was thought to rule a lost Christian kingdom somewhere in the East and was ready to attack Muslim opponents with his enormous armies. There was apparent proof of Prester John's existence, in letters purportedly from him and in stories from travelers who claimed they had met, if not him, then people who had news of him. Most pointed to a home in the earthly paradise in the Indies, outside Eden, with fantastical animals and unimaginable riches. Later, Portuguese explorers thought they had found him in Ethiopia, despite the mystified denials of people there. Melvyn Bragg asks why the legend was so strongly believed for so long, and what facts helped sustain the myths. With Marianne O'Doherty Associate Professor in English at the University of Southampton Martin Palmer Director of the International Consultancy on Religion, Education, and Culture And Amanda Power Senior Lecturer in Medieval History at the University of Sheffield. Producer: Simon Tillotson.