'During the Cold War, defectors from the Russian Intelligence Services to the West were of critical importance. They exposed and neutralised hundreds of Soviet agents who had penetrated government departments and democratic institutions. Stretching from Anatoli Granovsky in 1946 to Oleg Gordievsky in 1985, these Soviet defectors were highly prized for the intelligence they provided to security services. Ranked amongst the most valuable at the time was Vladimir Mikhailovich Petrov, who defected in Sydney in 1954. Yet he, almost alone, has overwhelmingly been cast by commentators and historians as lazy, inefficient, and incompetent. This article will offer an alternative interpretation of Petrov. My argument has three prongs. First, Petrov's contact with Russian individuals and pro-Soviet political organisations in Australia was far more extensive than generally assumed. Second, contrary to the historiographical consensus, he withheld intelligence about his contacts and informants from his security service debriefers. Third, rather than Petrov seeing espionage as too dangerous, as suggested, he was a committed and active Soviet intelligence cadre. By reappraising Petrov, the article seeks to provide a fresh understanding of this key episode, the Petrov Affair, in Australia's Cold War history.' (Publication abstract)