PC Bruno worked in close cooperation with Britain's decryption center at Bletchley Park.
In the early 1930s, French military intelligence acquired operation manuals and sample messages for the German Enigma cipher machine.
French intelligence officer Captain Gustave Bertrand supplied this material to Poland's Biuro Szyfrów ("Cipher Bureau"), which used it as part of their successful effort to break Enigma.
When Poland was overrun by Germany and the Soviet Union, the key staff of the Biuro Szyfrów were evacuated to Romania, and from there eventually reached France.
The Polish group was led by Lt. Col. Gwido Langer and included the mathematicians who had been breaking Enigma for nearly seven years since December 1932: Marian Rejewski, Jerzy Różycki, and Henryk Zygalski.
Henri Braquenié visited London and Bletchley Park, the British asked that the Polish cryptologists be made available to them in Britain.