Just over a year ago, the phone rang at the office of the Italian newspaper La Repubblica. A man asked to speak to Eugenio Scalfari, the paper's 90 year old founder and a prominent atheist. The caller was Pope Francis. And so began an unusual friendship, an unconventional piece of journalism and an unexpected glimpse into the character of a man who has taken the world stage by storm. Scalfari drew a picture of a "revolutionary" Pope, set on reforming Church bureaucracy, punishing paedophilia and re-examining priestly celibacy.

It's just one example of the style that has seen Pope Francis labelled the "cold-call Pope" - someone who has swapped the traditional, measured means of Papal communication for off the cuff statements and direct outreach to Catholics and non-Catholics alike. His informal approach has added to his mega-star popularity and fuelled hopes, and fears, about change in the Catholic Church.

For The Report, the BBC's Director of News and Current Affairs James Harding sets out to understand one of the world's most fascinating and charismatic leaders. How does Pope Francis really operate, does he herald a revolution in style or substance, and can his popularity survive in the face of such high expectations? As Church leaders gather in the Vatican for a Synod looking at how Church teaching concerning the family relates to the reality of modern life, The Report asks whether a "revolutionary" really has taken over at the Vatican.