Donald Trump’s reaction to the massacre at a gay nightclub in Orlando was revealing. “Appreciate the congrats for being right on radical Islamist terrorism”, tweeted the Republican party candidate for the US presidency.

Unlike conventional politicians, Mr Trump did not spend much time stressing his concern for the victims. In a later statement, he elaborated on his initial reaction: “I said this was going to happen — and it is only going to get worse?.?.?.?We can’t afford to be politically correct any more.”

For Mr Trump’s critics, his reaction to the murder of 49 people at the Pulse nightclub simply underlined his unseemly opportunism. But Mr Trump’s political instincts have proved very acute over the past year. His first principle is always to dominate the headlines. His second is that if there is a fire, to pour fuel on to it.