Wednesday, September 17, 2014

My Bletchley Pilgrimage

On my way home from Dublin to Valencia I stopped off in England. There the help of a younger relative enabled me to fulfil a long-cherished ambition. It was to make a pilgrimage to Bletchley Park (BP). BP is one of the places where programmable electronic computers were invented as a by-product of the Second World War (WW2). It is also where the father of computer science, Alan Turing, worked during that war. I saw his office, now stripped bare, and the little house in the stables area where he also worked. One guesstimate has it that the work accomplished at BP shortened the European war by two to four years and that without it the outcome would have been uncertain.

BP is at Milton Keynes, about an hour by car or by train (from Euston station) north of London. It was originally a fine country mansion in its own park before it was taken over by the British government for its Government Code and Cypher School (GC&CS) on the eve of WW2. For a long time the work done there was kept secret even after the war. Churchill didn't want the Russians to know about it. He even had its early computer, the Colossus, dismantled; though a replica has been rebuilt in recent years and is on view. Like many others, I first learnt about it with the publication of Winterbotham's book The Ultra Secret, in 1974 (see References). Since then numerous other books and articles have been published about it, Nevertheless I learnt many things on my visit and had some surprises. Here are my impressions.

Clearly BP needed a large and varied staff of cryptologists, translators, engineers, etc. However, the way the temporary wartime 'huts' were disposed throughout the grounds without ruining the park-like environment makes it difficult to imagine. In fact "in January 1945, at the peak of codebreaking efforts, some 9000 personnel were working at Bletchley." They used some 400 teleprinters. One wonders where they put them all.

The fact that the BP site was taken over on the very eve of the outbreak of war might lead one to think that the British were poorly prepared for the cryptology tussle. There was, however, a long continuous history behind it that went back to the First World War. The GC&CS began in 1919 in a room, Room 40, at the Admiralty in London. Three outstanding personalities symbolise its continuity. One of them was Commander Alistair Denniston, who was its operational head from 1919 to1942. As such he initiated and supervised the move to BP. It was also Denniston who realised that the enemy's use of electromechanical cipher machines meant that formally trained mathematicians would be needed to decode them. Another was Dilly Knox, a papyrologist who turned cryptographer back in Admiralty days and became BP's head cryptographer until his very untimely death in 1943. And the third was none other than Winston Churchill, who was First Lord of the Admiralty when Room 40 was established in WW1 and continued his support as Prime Minister into WW2. When a group at BP complained about insufficient resources, he wrote a typical minute on their letter,
"Action this day make sure they have all they want on extreme priority and report to me that this has been done."

Enigma and Lorenz
Enigma is the German coding machine that everyone has heard of. It had a long history, starting as a commercially available device in the 1920s. However, the German army also came to have another, equally important machine, the Lorenz. It was important because once it was brought into service in 1942, it was used for high-level communication between the German High Command in Berlin and army commands throughout occupied Europe. It was therefore imperative to do the reverse engineering of it. BP cryptographers succeeded in deducing its workings without ever having seen one; which has been described as "one of the greatest intellectual feats of World War II." So I learnt at BP to distinguish between the Enigma and the Lorenz, each with different workings and a different target.

Between the wars: the Poles
One of the surprises at BP is the monument to three young Polish cryptographers.

The first to discover the wiring plan of Enigma were not the British but the Poles. The Polish equivalent of GC&CS was already intercepting German Enigma traffic throughout the period 1930-1938. In 1928 an alert Polish customs officer had intercepted an Enigma that was being shipped to the German embassy in Warsaw, and that enabled the Polish Cipher Bureau to examine it. A team of brilliant mathematicians was recruited at Poznan University to work on its cryptology. Most of their work was based on a branch of pure mathematics known as permutation theory. They succeeded, and in 1938 they made a generous gift of their findings to French and British delegations. The British one included Turing and Knox. Their contribution to the British side of the cipher war was invaluable.

The translators
Once the wireless traffic was decrypted, it was still in German. For it to be useful to British intelligence, a large staff of specialised German to English translators had to work in shifts around the clock. There were nothing like enough Professional or Expert Military Translators available to meet the demand. But fortunately there was a good supply of Advanced Native Translators, because German language and literature was still widely taught in British secondary schools. (That's how I learnt it myself, even while the Germans were bombing us!) So graduates from the 'grammar schools', having learnt one foreign language and probably more, were considered prime candidates for further training.

The situation was not so favourable for other languages except French. Among the languages needed was Italian. Though the use of Italian was not comparable to that of German, it was Italian decrypts that enabled the British to win the Battle of Cape Matapan in 1941. The British fleet commander came personally to BP to thank the cryptographers.

I'll deal later with Japanese.

To be continued.

Group Captain F(red) W. Winterbotham, CBE. The Ultra Secret. New York, etc.: Harper & Row, 1974.

Bletchley Park official website.

Bletchley Park. Wikipedia. or click here.

John Pether. The Post Office at War. Bletchley Park Reports 11. Bletchley Park Trust, 2011.

Frank Carter. The First Breaking of Enigma. New edition. Report 2. Bletchley Park Trust, 2008.

The Bletchley Park Reports are available on site at BP.

Battle of Cape Matapan. Wikipedia, 2014.

There are good videos, some of them complete BBC documentaries, about BP on YouTube.

The Mansion at Bletchley Park. Source:


  1. Kevin,
    Hi. Sounds like you had a fascinating time at BP. Certainly you wrote it up very well indeed. I enjoyed every word.

    1. Thank you, Steve. More to come.

      By coincidence, while I was in England my wife was making her first visit to Portugal. Porto-Sintra-Lisbon. She fell in love with the country and says we should move there!

  2. What an immense read, post more often please! 
    Is there any further reading you would recommend on this?

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