When George W. Bush made his last visit to the Middle East he was greeted with a volley of shoes, a mark of contempt that measured with lamentable accuracy the level to which America’s reputation had sunk in the region during his eight long years in power.

Barack Obama, in his speech on Thursday to the Arab and Muslim worlds from Cairo University, arrived to a standing ovation and left to rapturous applause. He has started a new conversation. While all now depends on what the US does rather than what its president says, Mr Obama has changed the tone of relations between the west and the world of Islam.