Pope Francis has honoured his predecessor Benedict XVI, presiding over a rare requiem Mass for a dead pontiff by a living one in front of thousands of mourners in St Peter’s Square.Bells tolled and the faithful applauded on Thursday morning as pallbearers carried Benedict’s cypress coffin out of the fog-shrouded basilica and rested it before an altar.Francis, wearing the crimson vestments typical of papal funerals, then took his place and opened the Mass with a prayer.Heads of state and royalty were among those mourning on Thursday.