The essence of Donald Trump’s free-wheeling, mesmerising press conferences can be captured in the moment before he selects a question. 

Eyes narrowing behind the podium, the US president more often than not raises the index finger of his right hand but then pauses, surveying the room. 

Journalists push their hands into the air as high as possible. Shouts of “Mr President, Mr President” follow. Sometimes reporters jump to their feet in the hope of selection. 

And Mr Trump watches. Only for a second or two, but longer than other world leaders do. Sometimes he twirls his finger in indecision. And then the arm comes down, selecting the winner with a ‘you’re hired’ flourish.

This is where Mr Trump,…