<p>Kim Philby, the so-called Third Man in the Cambridge spy ring, was the Cold War's most infamous traitor, a Soviet spy at the heart of British intelligence. Philby joined Britain's secret service MI6 during the war and went on to head the section tasked with rooting out Russian spies before becoming the service's chief liaison officer with the CIA. He betrayed hundreds of British and US agents to the Russians and compromised numerous operations...