Not only was Pope Benedict XVI the oldest Pope to take up office but he came with a reputation as the most conservative of Popes and a fierce guardian of the truth. Yet by resigning he's overturned centuries of papal tradition and paved the way for a radical transformation of the Papacy and its relationship with the worldwide Catholic Church. It was a move which has sent shockwaves through the Catholic Church worldwide. For many it seemed so out of character but was it? Edward Stourton has been reassessing Pope Benedict's life and looking for clues as to what's really driven him during his long career. With the help of those who know him well and those who have followed him closely he has painted a somewhat surprising portrait of a Pope who was more radical than many might think.