The ultra-secret "Berlin Tunnel" was dug in the mid-1950s from the American sector in southwest Berlin and ran nearly a quarter-mile into the Soviet sector, allowing the CIA and the British Secret Intelligence Service (SIS) to tap into critical KGB and Soviet military underground telecommunication lines.
George Blake, a trusted officer working in a highly sensitive job with SIS, was privy to every aspect of the plan. Over the course of eleven months from May 1955 to April 1956, when the Soviets discovered the tunnel, "Operation Gold" provided seemingly invaluable intelligence about Soviet capabilities and intentions. The tunnel was celebrated as an astonishing CIA coup upon its disclosure, and the agency basked in its new reputation as a bold and capable intelligence agency that had, for once, outwitted the KGB. But in 1961, a Polish defector shocked the CIA and SIS by revealing that Blake was a double agent who had disclosed plans for the tunnel to the KGB before it was even built. Blake was arrested and sentenced in 1961 to 42 years in prison, the longest term ever imposed under modern English law. In the years since, the tunnel has been labelled a failure, based on the assumption that the Soviets would never have allowed any information of importance to be transmitted through the tapped lines. Not so.
In a work of remarkable investigative reporting, Steve Vogel now reveals that the information picked up by the CIA and SIS was more valuable than even they believed. But why would the Soviets, knowing full well that the tunnel was there, have let slip many of their most valuable secrets? Or did they actually know?
AGENT DIAMOND AND OPERATION GOLD draws upon a vast array of formerly classified documents from the National Archives, the CIA's Historical Review Program, the National Security Agency, the National Security Archive, the National Cryptologic Museum, the archives of the Stasi, the Federal Archives of Germany, the Imperial War Museum, and the U.K. National Archives, among others, including in the relevant records for the Prime Minister and the Ministry of Defence. Among those Vogel has interviewed is George Blake himself, now in his 90s, at his home in Moscow.