Bletchley Park – Hugh Davies 13th October 2014.

Hugh said that the digital age started at Bletchley Park.

Many of the machines were operated by WRENS where the work force was three women to one man.  Sixty per cent were uniformed personnel and forty per cent were civilians.  Rank/status within the uniformed ranks didn’t matter, so if any army private was intelligent and capable enough, he could be promoted to major within a week.

Hugh mentioned that the computers were needed to find out what the capabilities of the enemy were and what their intentions were.

Messages were sent in code and the interpretation of messages and breaking the code was paramount. The human factor came into play as, having intercepted the message, they then had to decide what to do with it and to whom they would send it, so a lot depended on human judgment and decisions.  He stressed that once any message was “in the airwaves” there was no privacy as it could, if the person had the right resources,  be retrieved but still needed to be decoded.  Basically the sender used a machine to transmit the message in code to the recipient who had a similar machine programmed with the same code, thus cutting out a possible interceptor.

Messages could be in codes which had hidden meanings e.g. “it is raining in Liverpool today” or in an extinct language e.g. Navaho.  The book Rebecca was used when statements such as 10 to 5 meant page 10 word 5 etc.  The Germans were alerted to this fact and bought the complete stock of Rebecca  novels in Spain.

Ciphers… these were substituting one letter for another. A polyalphabetic cipher alters a letter every time it is used.

Messages were intercepted by listening out stations and sent to Bletchley Park. Once decoded they were distributed to government offices i.e. the Air Ministry. Distribution was equally as important as the collection of messages because only the very top people were informed.

The Germans were convinced that their codes were unbreakable as if a computer is always random as its code could not be broken.  The element of non-randomness enables the code to be cracked by using greetings like “Happy Christmas” etc. and by using the same “sign off” words enabled the codes to be broken.

No one at Bletchley Park even talked about their work for over thirty years.  A husband and wife, married for many years, never knew that they had both worked at Bletchley Park.

So much interest was generated by the talk that that a  future visit to Bletchley Park by the club was proposed.