Bletchley Park was a well kept secret. All its personnel signed the Official Secrets Act and many of them carried the secret of what they did during the war to the grave with them. It wasn’t until the publication of F W Winterbotham’s book “the Ultra Secret” in 1974 that information began to appear in the public domain. Gordon Welchman published his own account of the Bletchley Park story in 1982 which revealed in considerable detail how the codebreakers were able to read the enciphered German messages. Since then numerous books have been published but it wasn’t until 2009 that the work of Bletchley personnel was recognised by the Government by a commemorative badge.
The work done at Bletchley Park in deciphering what the German’s regarded as an unbreakable code is credited by shortening the war by 2-4 years and ensuring an Allied victory. The close working relationship between the UK and USA fostered during the war still exists today. The work of the code breakers also led to the development of modern computers and the digital age.
After the war all personnel were demobilised and all the equipment was either broken up or moved to GCHQ in Cheltenham. Only one Bombe machine out of the nearly 400 in use during the war survives in the USA and this is no longer in working condition. By 1991 the site was derelict and at risk of demolition. Milton Borough Council were foresighted enough to declare the Park a conservation area and the Bletchley Trust was set up to maintain the site as museum. Buildings have been restored and it is now a very popular tourist attraction, concentrating on the work of the British code breakers to crack the enigma code which the Germans believed to be undecipherable.
When war was increasingly looking likely, the Government Code and Cipher School with its operational Head, Alastair Dennison, was looking for a place outside London. ‘Captain Ridley’s Shooting Party’ were a group of wealthy young friends who were exploring the huntin’ and fishin’ possibilities of the area, complete with their own chef. They were in fact looking for a suitable location well away from London to use a a base for their activities. Bletchley Park was ideal as it had good links to both London and the rest of the country. There were even plans to move to Canada if Britain was invaded.
It had a railway station within a short distance of the house and was near the A5. It was close to the main GPO trunk line with teleprinter connections and would be an ideal centre for the large spider’s web of communication lines. Between Oxford and Cambridge, it proved a fertile hunting ground for some of the best academic brains in the country and most of the early recruits came from them.
Personnel moved here in early January 1940. Beginning with 200 personnel, this increased to over 9000 by the end of the war. The brightest mathematical brains were recruited as well as those with a gift to crack ciphers and cryptic crosswords. Large numbers of clerical staff, mainly women, were recruited for the long boring and repetitive tasks.
A few people lived on site in the cottages behind the main house. The majority were billeted in the local area and either rode their bikes to work or were bussed in.
By the end of the war, there were over 100 drivers working here covering 32,000 miles a week providing transport for staff to and from their billets as well as chauffeur services for senior management. They had their own hut near the main gate by the military transport section. This housed the coaches, utility vehicles and service cars.
No-one in the area knew what Bletchley Park was doing. Many locals thought it was a mental hospital and this view was encouraged by the senior staff at Bletchley.
Security in and out of the grounds was tight with a 24 hour manned guard post and gates. The main canteen was built on Wilton Avenue, just outside the main gate. This could feed 1000 personnel at a time.
Initially all work was based in the main house, the “Mansion”:http://wasleys.org.uk/eleanor/presocialhistory/socialhistory/social/social/bletchley_park/mansion/index.html along with the stable block and the cottages. It soon became apparent more working accommodation was needed. A series of timber and plasterboard huts with brick built blast walls at the north end, were built to house the different operations. “Huts 3”:http://wasleys.org.uk/eleanor/presocialhistory/socialhistory/social/social/bletchley_park/hut_three/index.html and “6”:http://wasleys.org.uk/eleanor/presocialhistory/socialhistory/social/social/bletchley_park/hut_six/index.html worked on information from the German army and air force. “Huts 4 and 8”:http://wasleys.org.uk/eleanor/presocialhistory/socialhistory/social/social/bletchley_park/hut_eight/index.html worked on naval intelligence. One of the huts dealt with the incoming encrypted message. The other hut worked on the decoded messages. Each was a self contained unit with toilets, coffee room and cleaning staff. The huts were very basic with no insulation. The only form of heating small paraffin stoves. people either froze in the winter months or fried in the summer.
The first Bombe machine was housed in Hut 1. As more arrived, Hut 11 was built to house them. This was the first brick built building specially designed to protect the Bombes in case of enemy attack. The building was screen by trees and shrubs making it less obvious from the air. As more and more Bombe machines were delivered, they were housed in smaller outstations of 10-20 machines scattered around the local area. Hut 11 became the control and communications centre for all the Bombe machines. It now has a display on the Bombes and the Wrens who operated them.
Later more substantial buildings were constructed from reinforced concrete. The teleprinter building was in Block A. “Block B”:http://www.silvertraveladvisor.com/review/attraction/169773 housed the sections responsible for breaking Enigma ciphers from across Europe and later Japan. Block C contained the data processing machines and was the registry keeping records of all messages received.
Radio operators, usually Wrens, in Y stations across Britain, listened to all German radio messages. They became so adept that not only did they recognise the location of the transmission, very often they could also identify the person transmitting the message. The five letter codes were sent to Bletchley either by courier or by GPO teleprinter. The messages went to the Registration Room in either Hut 6 or Hut 8 and were transferred to punch cards. Messages were cross indexed for common messages like “weather report’ or ‘Heil Hitler’ which could be used as a crib to identify the key setting for the encoded message. The Crib was sent to the Bombe machine to crack the cipher key.
When a possible setting was discovered, the bombe stopped and the key codes were sent to the Machine room for checking. Once the correct setting for that day was established, the rest of the messages could be decoded using a Typex machine which was a modified Enigma machine designed for this purpose.
The messages were finally translated into English and passed onto the assessors who were intelligence experts who could evaluate the importance of the message before passing onto the advisors for comments and deciding who the messages, now termed “Ultra” should be sent to.
The messages were sent by motorbike courier or teleprinter to a separate small radio station based at Whaddon Hall, five miles from Bletchley Park. From here they messages were sent in morse code to MI6, senior army, navy and RAF personnel. Once the message had been read, it was destroyed.
The system was also used to send out misleading messages for the Germans to pick up, as was done very effectively in the run up to the D Day landings.
All staff signed the Official Secrets Act when they were recruited and were not allowed to talk about their work to anyone outside their hut. Work for the army, navy and airforce was also kept separate. Even physical communication between the huts was kept to a minimum. Huts 3 and 6 which needed to work closely together had a small ‘tunnel’ between them with closed doors at either end. Information was pushed between the two huts using a tea tray and broom handle. This secrecy was rigidly adhered to by all personnel, even many years after the war.
Many of the staff were in their early twenties and were encouraged to make their own entertainment. There was a tennis court and rounders was popular. Hut 12 became the entertainments hut where musical recitals were held and drama groups put on reviews and shows. Well known entertainers were brought in to entertain the workers.
The Germans were completely unaware of the work being carried out at Bletchley Park. Even thought the British were using the information received they were very careful to hide their source and the Germans believed it had come from people on the ground or from aerial reconnaissance. A few bombs were accidentally dropped here by German bombers but all they did was break a few windows.
There is a lot more detail and pictures “here.”:http://wasleys.org.uk/eleanor/presocialhistory/socialhistory/social/social/bletchley_park/index.html