Part 1 – Bletchley Park

The year is 1938 and the threat of Hitler and war was growing rapidly.The Government Code and Cypher School, then based in London, needed a safe home for its intelligence work to carry on uninterrupted by enemy air attacks. Strategically well placed at a junction of major road and with excellent rail connections to all parts of the country, Bletchley Park was ideal so the British Government purchased the estate.

Under the command of Alastair Denniston, Bletchley Park was assigned the name ‘Station X’. The codebreakers arrived in August 1939 under the guise of ‘Captain Ridley’s Shooting Party’. More ‘guests’ quickly followed including perhaps its most famous resident, Alan Turing.

During the war, the ENIGMA cypher was seen as the highest prize of the German military and intelligence communications. Invented in 1918, ENIGMA’s complexity was overwhelming and German intelligence was sure it was unbreakable. However, the Poles had broken ENIGMA in 1932, when the encoding machine was undergoing trials with the German Army and had even reconstructed a machine.

In July 1939, they passed on their knowledge to the British and this enabled the Bletchley codebreakers to better understand the workings of the ENIGMA. In particular the order in which the keys were attached to the electrical circuits. Bletchley Park’s codebreakers were able to exploit a chink in the machines armour. A fundamental flaw meant that no letter could ever be encrypted as itself. This gave the codebreakers their way in and errors in messages sent by German operators also gave vital clues.

January 1940 and the first break came into ENIGMA. Initially the codebreaking process was long and laborious. To speed up the process, Turing, working out of Hut 8, developed an idea originally proposed by Polish cryptanalysts. The result was a machine he called The Bombe: an electro-mechanical machine that not only greatly reduced the odds but also the time required to break the daily changing ENIGMA keys. It is widely believed that the work Turing and his colleagues did in Hut 8 helped shorten the war by two years and save millions of lives.

At the end of World War II and with the advent of the Cold War, Churchill believed it was vital that the USSR, Britain’s former ally, should learn nothing of Bletchley Park’s achievements. The thousands who had worked here departed. Some continued to use their remarkable expertise in the Government Communications Headquarters, better known as GCHQ. In 1987, after a fifty-year association with British Intelligence, Bletchley Park was finally decommissioned.

Today, Bletchley Park welcomes visitors from all over the world both young and old. People who survived the war thanks to those who worked there and others whose very existence would not have been if it hadn’t been for those who worked there. At its peak, some 10,000 people worked at Bletchley Park, although the exact number is not known, even today. They tackled the most complex tasks of intercepting, deciphering, analyzing and distributing intelligence gained from enemy radio signals whilst their work remained shrouded in the highest levels of secrecy.