<p>Klop Ustinov was Britain's most ingenious secret agent, but he wasn't authorised to kill. Instead, he was authorised to tell tall tales, bemusing and beguiling his enemies into revealing their deepest, darkest secrets. From the Russian Revolution to the Cold War, he bluffed and tricked his way into the confidence of everyone from Soviet commissars to Gestapo Gruppenführer. In Klop: Britain's Most Ingenious Secret Agent, journalist Peter Day br...