Sir Charles Rodger Noel Winn, CB, OBE (22 December 1903 – 4 June 1972) was a British judge and Royal Navy intelligence officer who led the tracking of German U-boat operations during World War II.
But he was soon assigned to the Admiralty's Submarine Tracking Room (part of the Operational Intelligence Centre – OIC), although he was still a civilian.
It is a measure of his ability that he received this rank and position without formal naval officer training, which was unprecedented at the time, and that he displaced his former superior.
His arguments and expertise proved effective; he managed to persuade Admiral Ernest King (the formidable USN commander in chief), to implement a convoy system.
From ULTRA and his observations of U-boat movements, he deduced that German codebreakers had cracked the BAMS (Broadcast to Allied Merchant Ships) code used by the Admiralty for convoy operations.
After the war, captured records showed that the German Navy's Beobachtungsdienst (Signals Intelligence Service) had been reading BAMS since the start of the conflict.
He arranged for a double agent to send a bogus message, warning the Germans of a new British minefield "where [the U-boats] go to fix their position."