Code Breakers Bletchley Park’s Lost Heroes

The Lorenz machine was used by the Germans to encrypt high-level teleprinter communications. It contained 12 wheels with a total of 501 pins.

I’m a fiend for the efforts of the British secret service to decipher the German codes during World War II and this BBC documentary examines two of the lesser known heroes of this secret war. William Tutte at Bletchley Park, by looking at an intercepted message, figured out how the German Lorenz cipher machine worked without ever seeing one. He deduced the device had twelve encoding wheels by looking at the mind-numbing repetition of patterns in the encoded message.

A Colossus Mark 2 computer. The operators are (left to right) Dorothy Du Boisson and Elsie Booker. The slanted control panel on the left was used to set the “pin” (or “cam”) patterns of the Lorenz. The “bedstead” paper tape transport is on the right.

But knowing how the machine worked was only half of the victory. Tommy Flowers, who worked at a research division of the General Post Office, created the world’s first semi-programmable computer Colossus that would decode the intercepted messages. Even many people who know about Bletchley Park are unaware of the contributions of Flowers and Tutte, whose efforts went unsung for decades because of official secrecy.

This is a great documentary, even if one is left feeling stupid after hearing an explanation of how the code was broken and being unable to comprehend any of it. The documentary is narrated by Keeley Hawes, who starred in the BBC series Spooks.

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