Week 48, 2021 – Documentary

Bletchley Park Codebreakers

During World War I Britain built up a significant Signals Intelligence (Sigint) operation, listening to enemy radio traffic. The Government Code & Cypher School (GC&CS) was created at the end of the war and developed over the next two decades.  Bletchley Park housed the British codebreaking operation during World War II and was the birthplace of modern computing.

Historians estimate that the Codebreakers’ efforts shortened the war by up to two years, saving countless lives. At its peak, around ten thousand people worked at Bletchley Park and its associated outstations.

In 1938 Bletchley Park was bought by the Head of MI6. In August, a delegation from MI6 and the Government Code and Cypher School (GC&CS) spent around a month at Bletchley Park.  To disguise their true identity, this delegation masqueraded as ‘Captain Ridley’s Shooting Party’. By 1939 veteran cryptanalysts from World War I plus linguists and classicists such as John Tiltman, Dilly Knox, Hugh Foss, and Frank Birch formed the core of GC&CS’s expertise. They were joined by men and women recruited from industry and other branches of academia.

Bletchley Park staff worked on an 8-hour shift system: 8 am to 4 pm (days), 4 pm to midnight (evenings), and midnight to 8 am (nights). However, it was not all work – The Bletchley Park Recreational Club included a library, drama group, music, and choral societies as well as bridge, chess, fencing, and Scottish dancing.

Many romances blossomed here and numerous couples went on to marry. However, they had all signed the Official Secrets Act and kept their vow of silence until the story of what was achieved here began to emerge in the 1970s. Even now, some Veterans remain tight-lipped about their part in the codebreaking operation because they had been sworn to secrecy.

ENIGMA, an electro-mechanical cypher machine, was adapted for use by the Wehrmacht (German Armed Forces) and became the most widely used German encrypting device in WWII.

Ultimately, Enigma cypher machines were used by all three branches of the Wehrmacht: Heeres (Army), Kriegsmarine (Navy), and Luftwaffe (Air-Force). Enigma was also used by the Japanese and Italians to encode secret messages.