British SigInt

Origins

The roots of the British SigInt (Signal Intelligence) can be traced all the way back to 1653, with the postal monopoly and the Secret Office. This period of the British SigInt lasted until 1844. It wasn't until the first world war in 1914 that the British SigInt came back to life. By the end of the war England had a considerable SigInt group comprised of about 200 people but this group was decentralized and barely manageable.

Between Wars

The Government Codes and Cypher School (GC&CS) was a peacetime organization that resulted from the success of the SigInt during World War I. The GC&CS performed both cryptography and cryptanalysis. GC&CS began as an external resource to various services and agencies such as the Metropolitan Police and the Army and Navy. Soviet and German signals were the most frequent traffic signals being monitored by the GC&CS. The Official Secretes Act of 1920 allowed such interceptions during peace time. The years between WWI and WWII consisted of various foreign governmental movements such as the Bolsheviks uprising in Russia and Germany's rise to military power. The following quote from the head of GC&CS Alistair Denniston, would sufficiently describe the GC&CS during the inter-war years:

"We stared in 1919 at the period of bow-and-arrow methods, i.e. alphabetic books; we followed the various developments of security measures adopted in every country; we reached 1939 with a full knowledge of all the methods evolved, and with the ability to read all diplomatic communications of all powers except those which had been forced, like Germany and Russia, to adopt OTP." [8d] (OTP meaning one time pad).

1939

By 1939 the goals of GC&CS was made very clear. The GC&CS advised other services on the encoding and decoding security levels of various governments throughout the world. However, many of the services didn't seek information from the GC&CS all too often. Thus the GC&CS focused much of it's efforts towards signal intelligence. The GC&CS also extended its work in the commercial industry.

Another inefficiency of the GC&CS was that it primarily focused on foreign civilian interests. The organization was still decentralized in that services essentially had their own sections within the GC&CS. This meant that they had to conduct their own traffic interceptions and analysis. The head of the GC&CS wanted the organization to remain a cryptanalytic bureau as much as possible.

On the other hand, the GC&CS had many favorable advantages. Various teleprinter links throughout the vicinity connecting back to GCHQ had enhanced greatly before World War II. With the advent of war, in 1938 the GC&CS bought Bletchley Park and quickly installed communication equipment there. Many trial runs took place at Bletchley Park and recruiting from colleges and universities began to pick up. By August 1939, all parts of the GC&CS moved to Bletchley Park. During this time Denniston mentions:

"By September when war was declared, GC&CS was in action at its war station, already in process of growth towards that vast and successful body whose full story will perhaps never be told." [8d]

Commercially, the Enigma machine didn't present any major problems for the GC&CS but when the German army modified it by adding the plugboard it made it rather more difficult to break. During the summer of 1939, Denniston and a few other members of the GC&CS visited Poland. The Polish cryptanalysts gave them various documents of their Bombe and the Enigma rotor wiring. However, the German army once more made the Enigma process more complicated with a new way to configure initial settings. This discouraged the GC&CS and brought about a great skepticism that, what is seemingly impossible to do will, they felt, remain that way.