After the initial shock came the speculation. Pope Benedict XVI surprised even his closest advisers on Monday by announcing that he was standing down, but within hours the Vatican was awash, not just with the inevitable talk of who would succeed him, but also with whispers about the “real story” behind the first papal resignation in over 600 years.

Once the curia – or Vatican bureaucracy – started chewing it over, the theories it spat out were quickly flying around what the papal historian John Cornwell has characterised as “a palace of gossipy eunuchs”. And from there it is one short step to finding their way into the Italian press.

Dan Brown couldn’t have made it up. The ecclesiastical earthquake of a pope resigning has been attributed, variously, to Benedict nursing a fatal illness; to a head injury during his trip to Mexico last March that convinced him to abdicate; to being forced out after an acrimonious meeting with a group of senior cardinals two days before he announced his resignation; to his looming disgrace over either dodgy deals done by the Vatican Bank, past cover-ups of paedophile priests, or an “explosive” forthcoming report by a team of cardinals on a tendering scandal; and to a strategy to secure the succession for his favourite.

All of which at first glance makes me and many Catholics seem hopelessly naive for taking as read Benedict’s explanation in his resignation speech – namely that he was too old, physically and spiritually, to continue to be chief executive of a multinational church of 1.3 billion souls. Given that he is 85 and has always carried himself like a piece of delicate china, that sounded perfectly reasonable in worldly terms, even if it was a radical move in the history of the papacy, tantamount in some eyes to betrayal. (“One doesn’t come down from the cross,” Cardinal Dziwisz, former secretary to John Paul II, has remarked disapprovingly.)