VISIT TO STATION X, BLETCHLEY PARK

on 24 October 2002

Station X was the name of the radio receiving station set up by the security services at Bletchley Park at the beginning of the Second World War, in 1939. It gave its name to the site but was not of significant importance.

Bletchley Park, Buckingham is near the centre of England, had good road and rail connections to London, Birmingham, Oxford and Cambridge, and was close to a main Post Office cable repeater station between London and the important cities. This was important for the connection of teleprinters.

The Park was the home of the British code breaking effort, which eventually comprised 12,000 people, over 10,000 of whom were women - civilians and service women, often WRENS (Women's Royal Naval Service) - who shortened the duration of the war by two or three years. They achieved this by reading the messages of German, Japanese and other enemy forces, so that our commanders could be told their plans and movements.

They worked in wooden and brick huts in the grounds of the mansion, in Spartan conditions and in total secrecy. The inhabitants of one hut were not allowed into others or to wander the grounds and had 30 minutes for a lunch break, including the time to walk to and from the cafeteria, which was sometimes 10 minutes. Huts worked in pairs: one decoded messages, the other translated them into English and sent them on to our force commanders.

Two major coding machines were used by the Germans: Enigma and Lorenz. Enigma machines were also supplied to their allies and many thousands of them were used for day-to-day communications to and between forces in the field; the Lorenz machines were used by the High Command in Germany for communication with the most senior ranks on matters of strategy and policy.

The Enigma machine had a keyboard, 26 lights, 26 sockets and three wheels each with 26 settings.

By choosing the setting on the wheels and plugs (and selecting which three of five wheels to use), a light behind a letter was illuminated each time a key was pressed - but pressing the key again produced a different letter. The machine could provide millions of variations for one letter.

In the 1930s the Polish Intelligence Service had obtained an Enigma machine and instructions on its use with the help of a disaffected German clerk. They devised machines and methods for breaking the codes. During the '30s, Enigma used just the same 3 wheels in any order. This enabled the Poles to crack it by building 6 Bombes (one for each permutation). Then during the summer of 1939, the Germans added 2 more wheels, and Enigma ran with any 3 from 5 in any order, a total of 60 arrangements.This was too much for the Polish technology, and so they decided to hand over all their knowledge and tools to the Allies in 1939, when they could see that the invasion of Poland was imminent. They gave all this information to the French and British intelligence services. A memorial to the Polish Intelligence service was set up at Bletchley Park recently. But this was only the start; the German machines were changed and improved, so the codes they generated had to be broken again. The code breakers were recruited from universities and known puzzle-solvers and often worked throughout the night at crucial times. By 1944 they were receiving 30,000 messages a day and decoding a substantial proportion of them.

There were two main Enigma streams: from the German Army and Air Force, and from their Navy. In the early war years the Navy messages were the most important because of British losses of ships in the Atlantic from U-boat attacks. But these messages were more difficult to decode and it took about two years to break them. The Army messages were more numerous and sometimes the operators were careless in sending them and the code breakers could take advantage of this.

To speed up the decoding several machines were built and examples of these were on display. The Polish `bomba' was reproduced and developed as the Turing/Welchman Bombe, a working version of which is under construction.

This was followed by the Collosus, the world's first programmable electronic computer. This was used to decode Lorenz. A model has just been built and run, with the Tunny, which takes its output for further processing. With these machines a success rate of 97.6% was achieved in decoding Enigma and Lorenz messages.

Collosus

Collosus Valves

There is an extensive display, The Cryptology Trail, that explains how the messages were intercepted at Y-Stations all over the world, sent to Bletchley Park by dispatch rider or teleprinter, decoded, translated and sent out to our forces using our version of Enigma (Ultra). We had two hours to see it all - you need two days or more to understand it thoroughly. It is well worth a visit to do so one weekend or weekday afternoon. On the site there are also exhibitions of wartime uniforms, transport, electronics and radio, cinema projectors and Churchilliana. Also a Toy Museum, Model Railway, Fire Museum and Boat Club.

In the shop an interesting book which explains what life was like at Bletchley is on sale: Top Secret Ultra by Peter Calvorcoressi. Also see www.bletchleypark.org.uk and the report on the lecture: `Breaking the Lorenz Ciphers' by Frank Carter in this volume of the Proceedings.

Donald Lovell