Tyler Cowen informs us:
Marginal Revolution: Arthur Pigou wasn't a KGB agent after all: Or so it seems. For twenty-five years I thought he was. As I recall, the John Costello and Richard Deacon books said he recruited impressionable young British men to the Soviet side. Now, using Google BookSearch I read that he was mistakenly accused. Pigou, by the way, no matter what his politics, remains one of the most underrated economists. He was, among other things, also a father of behavioral economics.
Wouldn't it have been "an NKVD agent"?