#mims30by30 20: Bletchley Park 

Completed: Thursday 10th August 2017

I’ve had an interest in the 1940’s and 50’s for a few years since being invited on a 1940’s reenactment weekend. The following year my friend and I decided to start jive lessons as our new year’s resolution, and we haven’t stopped. The clothing, music and dancing became a big part of my social life which I love. During this time the film ‘The Imitation Game’ came out starring Benedict Cumberbatch as Alan Turing, the code breaker who contributed enormously to solving the unbreakable Enigma code. This sparked my interest for Bletchley Park and wanting to see where it all happened. It was a fascinating day including a free hour long very informative guided tour to the outside of all the important buildings. This allowed us to visit inside afterwards and make the most of the updated and interactive activities. The buildings are simple and unassuming yet what took place inside is a world away from this.

Samuel Leon had bought the Bletchley Park Estate in 1882 and a year later moved in having many rooms added to the original house until 1905. The estate went up for sale in 1937 and eventually bought by a builder, but by mid 1938 the head of MI6 Sir Hugh Sinclair, with the start of another war likely, had the foresight to buy the estate off him. It is the ideal location for intelligence services; rural setting of the house and fields but directly opposite Bletchley station with good transport links to the rest of the country including London, Oxford and Cambridge. There is a yard at the back of the mansion and a row of three cottages. There was plenty of space to build huts and expand the buildings as the personnel grew from a few hundred to over 9000 by the end of the war. Very few people lived on site, most worked in shifts and never had a day off but lived with families in villages in the surrounding area. There were three main entrances to the site, and a common scene was dispatch riders (up to 40 a day) on motorbikes going in and out the gates bringing original messages in pouches they had collected to be cross checked with deciphered codes.

Bletchley Park was effectively a secret world during the second world war. No one knew what happened inside the gates – not even the workers knew what was happening in each hut apart from their own. The theory was that if people didn’t know, they couldn’t tell anyone else – and the theory worked. Every person who worked in Bletchley Park had to sign the Official Secret’s Act the day they started, and this lasted for thirty years after the war ended. They couldn’t tell their family or friends what they had really been doing all that time. Eventually in the 1970’s someone who had worked there talked about what they had been involved in, and over the years stories have come to light and the incredible work of the Bletchley Park codebreakers has been given the credit it deserves. I’m sure there are still secrets that haven’t ever been told, but we are so thankful for the tireless efforts of all those who worked for years to crack the enemy codes to save thousands of lives.

It can all sound very confusing when walking round and learning about the many amazing things they got up to. From what I can work out, this is a brief summary of the process of a message being sent between Germans…

  1. German message is written.
  2. German’s code the message on an Enigma machine reset to a different code everyday at midnight. There were ‘key sheets’ which told them what the settings for the Enigma machine were for each day of the month. These were vital pieces of intelligence for the Allies to get hold of. Different organisations had different key sheets so it was important they knew which to use.
  3. Coded message sent in morse code.
  4. Coded message received and written down.
  5. Message decoded using an Enigma machine set to exactly the same settings as the coding machine. The coded message would be typed on the keyboard and the original message would appear in the lightboard above.

The German’s saw the Enigma machine as being impossible to crack. It was originally deigned for commercial use but they were too expensive to buy. The machine looked like typewriters, but they had one specific purpose – to code and decode. Above the normal keyboard was a light board which showed the coded letter of the key you had just hit. At the top were three cogs each with 26 letters of the alphabet on. Although there were only space for three, there were five possible cogs that could be used in any order.  However, there were slight flaws in the process…as the machines were reciprocal (so that messages were decoded directly in reverse) no letter would ever be coded as itself – when the Allies worked this out, we realised it greatly reduced the number of possible combinations. Another helpful design fault was that once a letter had been pressed the right hand cog would turn one setting (until it had gone through all 26, then the middle cog would turn and so on), meaning no coded letter would ever appear twice in a row, which also contributed to speeding up the cracking of the machine.

At point 3 in the above process is where Bletchley Park got involved…

  1. The morse code messages would be intercepted and written down. They were usually sent and written down in blocks of four letters at a time.
  2. The codes would be passed to the code breakers to try and identify any patterns. This may be a code (eg whole words replaced by another word) or a cypher – individual letters replaced for other letters, which is what Enigma was used for.
  3. Once it had been developed, the code would be put in to the Enigma cracking machine the ‘Bombe’ which would work out what setting to have the cogs on the Enigma machine for that day.
  4. Enigma would be set to the right settings and the coded message would be typed in. Someone would record the lights on the board which would be the original message.
  5. The original message was then translated from German to English, and passed to the officer in charge.

Someone worked out from triangulation of traffic analysis (where the morse code messages were coming from, time of day, etc) that the German messages were sent from off shore but a stationary point at the same time each day. They correctly predicted this meant it was a weather station, and therefore made a weather report at the same time each morning. The Allies were then able to identify common words used each time to help them know which letters were set to which codes for that day.

When Winston Churchill visited the site, he went round the various huts talking to the workers. He described the work as ‘ultra top secret’ and from then on if something had ‘ultra’ printed on it, it was higher than ‘top secret’ and there was a designated list of very few people who could see it.

Alan Turing has become a famous name of Bletchley, mainly from ‘The Imitation Game’ which is based on his life and work during the war. He was head of Hut 8 which was the Navel Decoding and Deciphering Department (Huts 3 and 6 were for Air and Army decoding), and his theoretical idea for the Enigma cracking machine – the Bombe – was turned into reality by a group of engineers. We have the Poles to thank a lot for this who had shared their intelligence of a basic similar system a few years previously. The Bombe machine has around twelve miles of cable, and about two hundred were made and distributed around the country. Six were held in Hut 11 on site at Bletchley Park. Most were dismantled at the end of the war as they had no purpose and their parts were useful for other things. Turing then also went on to develop Colossus which is known for being the first computer.

 

 

 

 

 

 

 

 

If you want to see where codes were broken, find out more here.

To see the full list of 30 things I’m doing, you can see the original post here.

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