Midway through the BBC’s ancient but still mesmerising adaptation of Tinker, Tailor, Soldier, Spy, there is a pivotal discussion between George Smiley, the hero of John Le Carre’s classic espionage tale, and the promotion-hungry Toby Esterhase, one of several colleagues implicated in an MI6 palace coup.
Smiley attempts to sweet-talk his man into divulging information by suggesting that “Control”, the boss of the secret service, might “move him up a few rungs”. To which Esterhase replies: “Actually, I’m not sure he is able to these days. Are yo...