Bletchley Park
In 1939, in Warsaw, the Polish military showed French and British intelligence agents their cryptanalysis of the Enigma. They promised each delegation a Polish-built Enigma. Having an actual Enigma machine, and knowing how to use it, was a much-needed start for the British work at Bletchley Park. Dilly Knox and Alan Turing were later joined by many other codebreakers and engineering staff.