GCHQ started life during the first world war. Its most notable success of the time being the interception of the telegram sent by the German Foreign Minister, Count Zimmermann. This detailed that the German forces were going to start unrestricted attacks on all shipping, including neutral American vessels. It also detailed promises to Mexico of giving her U.S. states in return for entering the war on the German side. This incident was crucial in bringing the U.S. in to the war on the side of the British.
With the end of World War One, the importance of intercepting enemy communication was not lost. The Government Codes and Cypher School (GC&CS) was created to continue the work in peacetime. In 1922, the school was passed from the control of the Admiralty to that of C, the commander of SIS (MI6). In reality, it remained separate to SIS, choosing how it collected information and developed itself during this period.
With the slide towards war in the mid 1930’s, GC&CS extended its work to military and naval intelligence. After the Munich Crisis of 1938, a decision was made to move the school out of London to limit any damage the expected bombing of the city at the start of the war would have. The site chosen was Bletchley Park.
Bletchley is now almost common knowledge. A film has been made and Alan Turing, arguably the inventor of modern computing, has been held up as the hero he was and still is. The stories of Colossus and the cracking of the German Enigma code are no doubt rolling off the tongue of many school aged child. Even GCHQ’s own website details the operation, so there is no point in me retelling the story here.
What I find most interesting about this period, are the personalities. The story we are sold, includes a mere handful of people, Turing, Tommy Flowers etc, when in reality at its peak 10,000 people worked at Bletchley Park. One can reasonably assume, that this is a rather good indicator of just how secret GCHQ and the security services are of their work and how good they are of maintaining that secrecy. GCHQ’s website key figures of UK SIGINT (Signals Intelligence) but the last entry on this page is James Ellis, the inventor of Public Key Cryptography, who joined the service in 1952. Everything from the modern era is much less widely spoken about, although not completely impenetrable as you will see.