Pope Gregory appeared to be leading major reforms within the church including attitudes towards clerical celibacy. But while there may have been suggestions of a willingness to accept change and to be flexible in the face of changing pressures he was also capable of ruthless intolerance. He was accused of necromancy, torture of a former friend, assassination attempts and unjust excommunications. His conflict with King Henry iv, Holy Roman Emperor dominated the European stage in the 1070s and 1080s.

Conrad Leyser, associate Professor at Worcester College, Oxford helps Jonathan tell the story of a man billed as a reformer but whose reputation underwent a dramatic change during his time as head of the church in Rome.