Change!  Robert Grenier, former head of the CIA counter-terrorism centre, said: “As for British Intelligence, I suppose, but do not know, that they must be very unhappy. They are often exasperated, quite reasonably, with their American friends, who are far more leak-prone than they.

“In their place, I would think two and three times before sharing with the Americans, and then only do it if I had to. The problem with that dynamic is that you don’t know what you don’t know, and what opportunities you might be missing when you decide not to share. The Americans are doing a very good job of undermining trust, and the problem starts at the top.”