Train to Bletchley Park

I took a train from Euston to Bletchley Park.  There was only one other stop - Leighton Buzzard - honestly, some of these town's names are certainly interesting.

Bletchley Park was comprised of the Mansion (above), numerous other buildings, and "huts" where most of the deciphering was done. Everyone worked in isolation, not knowing what the others were doing. They worked 8 hour shifts which changed periodically.

The process of breaking codes and how the Enigma worked was extremely complicated. I've tried to depict some of the process here.

This shows the rotors of the Enigma and some of the many combinations the cipher could take.

Enigma works this way: Germans would encrypt a message and send it via Morse code. It was deciphered by typing the message into their own Enigma machine which would decipher it. Both sender and receivers had to have their Enigma machines set up with identical settings. These changed each day. 

Occasionally, the Germans used ordinary words for daily settings, like those of girlfriends or even four-letter words. These were called Cillis. Discovering what these daily settings were was a huge challenge. 

John Herival came up with the idea that the Germans were tired in the morning when they set the daily settings, so perhaps the settings might vary by only a letter or two or not at all. He turned out to be correct. This was a major breakthrough. 

Many workers cycled from where they stayed in the town to the Park. I don't know if these bicycles are original or just old. Above you can see how the cycles were kept upright with a concrete groove which held the back tire. One light is partially blacked out to limit the amount of light that got out.

Some of the many huts in the Park. 

As you can see, the hallways/huts were all original, even down to the chipped paint.

Black shades obscured the windows. The rooms/huts/buildings appeared to be left as they were when the war ended. The workers were told to lock the doors and leave.

The audio guide included fascinating commentary by those who actually worked at Bletchley. One man described how in Hut 6, they would break the daily settings for the Enigma, and then pass these decoded messages on to Hut 3 where they would be translated and analyzed. The photos below show how the papers were passed through a protected wooden chute in a desk tray which was pushed by a broom and then retrieved on the other end by pulling on a string.

 

Occasionally, the messages were sent by dispatch riders:

Eventually, Alan Turing's Bombe machine dramatically reduced the time needed to find the daily settings.