John le Carré was one of the more extraordinary popular writers of the last half-century (and more) and part of what makes him so extraordinary is the way he can confound the distinction between trash and treasure. He was also to an extraordinary degree a magnetic personality with performative skills to rival the starriest actor and these are on show with a mesmerising degree of dexterity and arguably disingenuous candour in the engrossing and bewildering new doco, The Pigeon Tunnel by Errol Morris which has just started screening on Apple+.