AFTER ALL THE voting cardinals have been herded inside the Sistine Chapel at the start of a conclave, the cry goes up from the papal master of ceremonies, “Extra omnes”, or “Everyone out”. He then closes the doors and voting begins. This ritual underlines one of the basic tenets of a conclave. The cardinals who vote for a successor to St Peter must do so without any outside interference, and in an atmosphere that allows for the “interior movements of the Holy Spirit”.

The strict rules about papal elections, codified by Pope John Paul II in his 1996 apostolic constitution Universi Dominici Gregis, arose out of centuries of occasional interference from European monarchs and came less than a century after Austro-Hungarian Emperor Franz Joseph used his veto in the 1903 conclave to prevent the election of the candidate with most support among the cardinals.