In 1982, a Royal Navy nuclear submarine stole the Soviet Union’s most secret listening device from behind a ship that was still under way. This is Operation Barmaid, the HMS Conqueror sonar array theft, and the Cold War intelligence operation Britain kept classified for thirty years. The Soviet crew towing it filed no report, because as far as they ever knew, nothing had been taken. ━━━━━━━━━━━━━━━━━━━━ THE STORY IN SHORT Autumn 1982, the Barents Sea. A Polish-flagged intelligence trawler tows a two-mile passive sonar array on a three-inch steel cable, the finest listening instrument in the Soviet fleet. HMS Conqueror, fresh home from the South Atlantic, arrives fitted with remotely operated steel pincers and television cameras on her bow. She climbs into the one cone of silence the array cannot hear, the water directly beneath the towing ship’s own keel. The cable is cut. The array goes

Source: Why The Soviets Never Realised A British Submarine Had Stolen Their Secret Sonar