7. England - Bletchley Park

The projected radio traffic of the German military machine was staggering! Consequently the Bletchley Park organisation had to be large, multispecialist, in tight control of the dissemination of the collected material and, above all, totally secret. In other words, the Germans should not be able to either penetrate it directly or deduce its existence by correlating their military orders with British counter activities. It was decided from the very beginning that keeping the Enigma decrypting activity secret outweighed any temporary advantages, however important. To achieve the above-mentioned requirements an organization called ULTRA was established and became the basis for the collection and dissemination of top-secret intelligence information. The basic rules were as follows:

1. The existence of Bletchley Park was to be totally secret and no Bletchley Park employee was allowed to be in circumstances that could possibly lead to capture by the Germans.
2. The unauthorised use of the code word ULTRA was strictly forbidden.
3. The list of the recipients for Enigma information was strictly limited to a grand total of nine:
   The Chiefs of Staff of the Army, Air Force and Navy
   The Chiefs of Intelligence of the Army, Air Force and Navy
   The Chief of Fighter Command
   The Chief of the Home Guard
   The Prime Minister
4. The dissemination of information was to be handled only by the Special Liaison Units (SLU) attached to Bletchley Park and respective recipients or by secure links. The recipient would be given the information by an SLU officer and at that time all the recorded information would be destroyed to prevent any dissemination to any person not on the list.
5. The dissemination of the information was to be controlled by the intelligence section which would have the authority to translate messages, sort them into categories, make comments and assign priorities. Any action taken by the recipient based upon the Enigma decrypt had to be strictly controlled to ensure that Germany could not guess that it resulted from breaking the Enigma code. There had to be other corroborative information gathered from other intelligence sources before this information could be used. This edict was strictly enforced by Prime Minister Churchill to prevent German intelligence from correlating any Allied activities with German commands sent through Enigma channels. Throughout the war names were being continuously added to cover the ever increasing number of fronts and activities. In 1942 an agreement to share this information with US Forces was reached and an American contingent was established at Bletchley Park. By the end of the war the number of Enigma Intelligence recipients had reached 40.

In the early days of the war when Britain was fighting for its very survival, the number of "Bombes" was a meagre 12 - barely enough to keep up with the demand. As the war progressed and military activities increased, the number of "Bombes" required to service the demand increased to a colossal 332 in 1944! The manpower required to perform these tasks required many specialists and a large number of dedicated workers. The Bletchley Park operation started at the beginning of the war with 200, reached 1,550 by the end of 1942 and peaked at over 6,000 by the end of the war. The security of the Ultra information required all employees to stay with the Bletchley Park operation to the end of the war and their outside activities were strictly controlled and curtailed.


The structure of the Bletchley Park operation consisted of four elements:

1. Intercept stations located outside Bletchley Park

   Chatham, located 40 km. west of London and specialising in Wehrmacht traffic
   Cheadle and Chicksand, located 80 km. N-W of London and specialising in Luftwaffe traffic
   Flowerdown and Scarborough, located on the east and specialising in Navy traffic
   As the war progressed more intercept stations were added at Gibraltar, Malta,

2. The cryptologists located at Bletchley Park and in selected places close by
3. The intelligence section located entirely in Bletchley Park
4. The Special Liaison Unit located at Bletchley Park

Enigma decoding in Hut 6	Hut 11, the Bombe room	The Colossus machine

All the intercepted messages were transmitted to Bletchley Park, either by courier or over secure lines. To achieve efficient and successful operation the sequence of activities and the necessary feedback to achieve the desired outcome was strictly controlled. All the intercept traffic arrived at "Hut 6" ( a general term ) which contained cryptologists, "Bombes" and staff that ran the operation. Feedback from Intelligence Section located in "Hut 3" (another general term ), based upon previously decoded messages and other inputs, decided which messages were to be given priorities and assigned resources. The decrypted messages were passed "next door" to adjacent "Hut 3" which performed translation, evaluation of intelligence contents, made comments about its reliability and selected the recipients. The dissemination was performed by various SLU couriers or by secure links. "Hut 6" also contained a Crib Section that monitored encrypted messages for any signs of procedures that might throw light on the contents of the message - such as address, title or irregularity in procedures. These bits of information allowed the cryptoanalysts to reduce the number of trials from billions to numbers that could be handled by electromechanical machines. The collection of these precious bits of information, which was started by the Poles in the early thirties, played a substantial role both in theoretical analyses and practical decrypting work. Some of the more important were named Cribs, Kisses, Herivel Tips and Parkerismuses. They were educated guesses from the encrypted text of the same messages encrypted with different keys, machine set-up quirks, repeated wheel order and patch panel settings. A library was established and all new messages were checked against this stored information for any sign of similarity with previously decrypted messages.