History Class, Uncategorized, World War 2

Guest Post by Mike Biles: The Ultra Enigma of Bletchley Park (Part II)


As I stagger towards the NaNoWriMo finish line this week (that’s not as much of an exaggeration as I’d like it to be) and prepare to celebrate Thanksgiving, I’m VERY thankful that I have another excellent guest post to share with you today. 

Today, author and blogger Mike Biles returns to share more of the fascinating story of the Second World War code-breakers of Bletchley Park. (If you missed Part One, here’s the link!)

Bletchley Park- home to British WWII code-breaking operations

Enigma was only part of the Bletchley Park story. As early as 1940, listening stations began to pick up enciphered teleprinter messages. These worked in a completely different way to messages enciphered on an Enigma and utilised two main types of even more sophisticated enciphering machines, the Geheimschreiber (secret writer) manufactured by Siemens and the more widely used Lorenz SZ40/42. The Lorenz had 12 rotors and used a one-time system which made the code unbreakable, unless you knew the settings. The code breakers recognised the messages for what they were, but were unable to read them. With no way of knowing what was being used to send the signals, either, they called the enemy machine ‘Tunny’ and the messages ‘Fish’. What they needed was someone to make a mistake to give them a way in and, in August 1941, that’s what happened.


An army operator in Athens sent a very long message to his opposite number in Vienna, who asked him to repeat the message because he didn’t get it all. So the obliging operator re-typed the message but, against all the rules, failed to reset the machine. Probably bored, this time the operator also abbreviated some of the text. The eavesdroppers at Knockholt listening post in Kent realised what had happened and swiftly sent the messages to Bletchley, where the veteran code breaker John Tiltman poured over them. Tiltman was able to get so far, but progress was slow. He asked a 24-year old chemistry graduate, Bill Tutte, to look at the problem.

Bill Tutte as an undergraduate at Trinity College, Cambridge, 1938.

Brilliantly, Tutte managed to construct the logical structure of Lorenz, without even seeing the machine, which provided the means of breaking the code. However, human brainpower alone was often insufficient to break Lorenz in time for meaningful intelligence to be extracted, so mechanical means were explored. The mathematician Max Newman and his team designed a creaky-looking machine they christened ‘Heath Robinson’, which worked but was painfully slow and unreliable. Turing recommended to Newman that an unknown but exceptional electronics engineer working for the GPO (General Post Office, forerunner of British Telecommunications) should take a look at the problem. The engineer was called Tommy Flowers and, starting in March 1943, he designed the world’s first practical electronic information processing machine – a computer. It was called Colossus and the first one was installed at Bletchley in January 1944. Colossus read teleprinter tape at 5,000 characters per second, meaning that Lorenz messages could be read in hours, rather than weeks. The second Colossus arrived in June 1944, just in time for D-Day, the Allied invasion of France on 6 June. Flowers’ achievement was outstanding. There were eventually ten Colossi at Bletchley Park. Two, it is said, were used by British intelligence up to 1960.

Lorenz was used to transmit very high level messages, including those of the OKW, the Oberkommando der Wehrmacht, or German High Command, and Hitler himself. Though its traffic was not broken in anything like the same quantity as Enigma’s, the quality of the intelligence was exceptionally high.


A Mark 22 Typex coding machine. This British equivalent of Enigma was used to key in decoded script to produce plain text German.

Of course, Germany wasn’t Bletchley Park’s only target. In addition to the Italian codes mentioned earlier, a separate team worked on Japanese codes, some of which had been broken by GC&CS as early as the 1920s. British code breakers initially worked on Japanese traffic in Singapore, switching to Colombo, Sri Lanka, and Kilindini in Kenya when Singapore fell in February 1942. As time went on, more and more work was carried out at Bletchley. SIGINT from Japanese diplomatic sources provided invaluable information about German activities, including advance warning of Operation Barbarossa, the German attack on the Soviet Union in June 1941, and vital information about German defensive plans in France.

Breaking Enigma, then Lorenz, was a progressive achievement. Some months were better than others, not every enemy message was read and, indeed, the Germans broke some Allied codes too. However, ULTRA produced spectacular results, some of which have been mentioned above. There are some contradictory claims, though, which might be inevitable given the nature of the beast. One documentary claimed that early decrypts revealed the hopeless British military position in France prior to Dunkirk and an interview with an ex-Bletchley worker suggested that an intercepted signal provided a vital clue as to the whereabouts of the pocket battleship, Bismarck, which enabled her to be tracked and sunk in May 1941. Another programme claimed that intelligence from Lorenz helped the USSR turn the tide against the Germans at the Battle of Kursk in 1943, because the Russians were supplied with a breakdown of the enemy battle order and attack plan. Other sources do not mention these successes, but of course an article like this one barely scratches the surface of such a large topic. What does seem beyond dispute is that SIGINT from Bletchley Park provided:

  • The locations of U-boats operating in the Atlantic;
  • Early warning of air attacks on Britain;
  • Intelligence in support of campaigns in North Africa and the Mediterranean;
  • Intelligence on new German weapons, including jets and atomic research;
  • Information on the German economy;
  • Full details of Italian deployments prior to the Battle of Matapan;
  • Intelligence to support the war against Japan;
  • The German battle order in Normandy prior to Operation Overlord (D-Day);
  • Confirmation of the success of Allied deception plans, including Operation Fortitude which convinced Hitler (against the advice of his generals) that the expected Allied attack would be made on the Pas-de-Calais area and that Normandy was a diversion.

In 1946, GC&CS Bletchley Park was wound down and closed. Its records, so ‘tis said (Bletchley apparently had, among other things, a detailed card index catalogue of erstwhile enemy military units) were cremated, its machines broken up and most of its staff returned to whatever they had been doing before the war. We believe that all the records were destroyed, don’t we, children? Anyway, nothing remained on site to provide the slightest clue to wartime activities. Its scaled back operations were taken up by the successor to GC&CS, the Government Communications Headquarters (GCHQ). Bletchley Park itself was subsequently used as a training college and saved from the bulldozers by a group of local historians in 1992. In 2014, it was officially opened by the Duchess of Cambridge as a visitor attraction.

The garages at Bletchley Park now contain some interesting restored vehicles from the time. This Packard Six sedan is one of a fleet purchased by SIS (MI6) in 1940. Their nice paintwork was replaced with camouflage and they were fitted with mobile radio transmitters so that they could act as independent mobile wireless stations. The cars were operated by SIS personnel as special communications units, passing on ULTRA decrypts to high level military commanders in the field personally. This version has obviously been returned to its showroom condition.


The Bletchley Park Trust, which runs the place, has done a cracking restoration job – which is ongoing. They have done their best to recreate the atmosphere of a government facility in wartime and, bearing in mind that contemporary photographs are as rare as hens’ teeth, have tried to recreate original layouts and details based on what primary sources they can find. Alan Turing’s tea mug, for example, is chained to his radiator, just as it used to be (so that no one else could borrow it). Audio-visual displays hint at the activity that must have taken place in the huts. Desks are laid out as though the occupants have popped out of the room 70 or so years ago, and forgotten to return. There are replicas of bombes, the world’s largest display of Enigma machines and, in the associated National Museum of Computing, a rebuilt Colossus computer.

Projected figures have whispered conversations in the restored huts. It’s very atmospheric!

In Commander Denniston’s restored office, a notice tells of a historic secret meeting that took place there on 8 February 1941, with four guests from the US intelligence community. The discussion concerned an exchange of information about Japanese and German codes. This was 10 months before the Japanese attack on Pearl Harbor and a huge gamble for both sides: the USA was not at war with anyone and not an ally of Britain’s. Whatever British Prime Minister Churchill and US President Roosevelt may have personally felt about the need to defeat Hitler, US public opinion was adamantly opposed to joining what was viewed as Europe’s war and there was some entrenched antipathy toward Britain. There were also, it must be said, some mutually disparaging views about each other in both countries’ military commands. The Americans visiting in 1941 had had a long and dangerous journey on an Atlantic convoy to wartime Britain. They reached Bletchley in the blackout and were given a glass of sherry. Important intelligence gifts were exchanged and the propaganda at Bletchley is that this was the start of the ‘special relationship’. Whether or not that claim is true (and this was not the first or only meeting between the two countries before the US entry into the war) intelligence collaboration between the United Kingdom and the United States grew, and by the end of the war had achieved an extraordinary level of closeness. US cryptographers served at Bletchley, bombes (and better ones) were built and used in the US.

Alastair Denniston’s office, where US intelligence officers discussed swapping secrets with Britain before USA was in the war, and where some believe the ‘special relationship’ began.

One of the fascinating aspects about any place where history has been made has to be the stories of those who made that history. You certainly get a sense of the ghosts of Bletchley as you walk its corridors, huts and grounds. And what an eclectic mix of people it ultimately was. Surprisingly – or maybe not surprisingly – there were active music, choral, dancing and, in particular, drama societies. The majority of personnel at Bletchley Park were women, working as code breakers, linguists, or in support roles. Wrens (members of the Women’s Royal Naval Service) were drafted in to operate the bombes; they were billeted at nearby country houses and the ‘Wrenneries’, as they were called, became renowned for their dances.

Faces – some of the people that worked at Station X.

I don’t suppose we’ll ever know what happened to all these people, who fought their own unique war for us without personally ever firing a shot. Because of the sensitivity surrounding Bletchley Park, but also because they were different times, it’s hard to avoid the conclusion that even those we know a little about have never received the recognition they deserve. Alastair Denniston (1881-1961) left Bletchley Park in 1942 and became a teacher after the war. Dilly Knox, born in 1884, died of cancer in 1943. Alan Turing (1912-54) was prosecuted for gross indecency in 1952 and opted for ‘chemical castration’ as an alternative to prison. He died of cyanide poisoning; his mother, and others, never accepted the official verdict of suicide. Gordon Welchman (1906-85) continued working in the clandestine communications world in the US, through the Cold War, and was treated as a pariah by the NSA (the USA’s National Security Agency, founded in 1952) and SIS after publishing ‘The Hut 6 Story’ in 1982. A documentary about his life claimed he was broken financially as a consequence. Tommy Flowers (1905-98) returned to working on telephone switchboards and appears to have been barely acknowledged for what he did until the 1970s. One happy story may be that of Bill Tutte (1917-2002), who became a renowned and highly respected mathematician, settling with his family in Canada.


The Alan Turing statue at Bletchley Park, created in Welsh slate by Stephen Kettle in 2007. It shows a slightly untidy Turing hunched over an Enigma machine and was commissioned by American businessman and philanthropist Sidney Frank.

From a point where few had even heard of Bletchley Park, there is now a plethora of available information about it. We don’t know, of course, how much of it is accurate. Claims that Bletchley Park’s achievements shortened the war by this or that period seem a little arbitrary. What does seem beyond dispute is that extracting the intelligence, and being able to act on it, saved millions of lives – not only the lives of those that consequently survived the war, on both sides, but also those who came later. It is no exaggeration to say that millions of people today owe their existence to those that worked at Station X. So, aside from this being a unique part of Britain’s heritage and an essential chapter in the story of the Second World War, it is easy to see why some believe a visit to BP could be akin to walking on hallowed ground. And, let’s face it, it is a portal into our age.

And what a fascinating portal it is! Thanks again to Mike for stopping by and sharing this story, and thanks to YOU, readers, for stopping by!


For more resources on Bletchley Park, and for information on Mike’s blog and book, read on!

Further reading and information:

The Bletchley Park website: https://bletchleypark.org.uk/

BP has an oral history project. If you know of anyone who lived or worked at Bletchley Park or in the area during World War Two, please contact them.

Both GCHQ and NSA websites contain some interesting information and there is a fascinating website based in the Netherlands dedicated to cryptography, which also includes the history – https://www.cryptomuseum.com/

There is no shortage of traditional reading material, including “The Secret War” by Max Hastings, which covers all aspects of espionage during WW2, and “Enigma” by Hugh Sebag Montefiore (whose family used to own Bletchley Park).

For more stories of Britain’s history and landmarks, during WWII and beyond, check out Mike’s site, “A Bit About Britain,” and his new book- more info below! 

Mike has lived in Britain all his life and generally loves the place, warts and all. He first learned history on his dad’s knee and went on to study medieval and modern British and European history at university. He was planning on teaching it, but then drifted into a career running his own business. Despite having worked with some of the UK’s most prestigious firms, he is often at his happiest with his nose in a history book, or exploring a historic site where the past is close. Several years ago, Mike began a blog – now an authoritative website – ‘A Bit About Britain’. He had to write a bit about Britain’s history for the website, and it seemed only sensible to put the material into his first book, ‘A Bit About Britain’s History’.

And as for Mike’s book (which I enjoyed very much!)…

Could this short, elegant, volume be the only book on British history you’ll ever need?

A Bit About Britain’s History is for anyone who wants a light introduction to Britain’s amazing story. If you don’t know the basics, or would like a reminder, this book is for you. It is also perfect for those that didn’t enjoy history at school, but who have suddenly realised they’d like to understand it a bit better now. Organised clearly and chronologically, A Bit About Britain’s History covers every period from a long time ago until quite recently. It begins by briefly mentioning that the place was once inhabited by extremely large lizards, and ends up with a post-war 20th century consumer society. Short articles explain the essential aspects of Britain’s past, including how the ancestors of its current inhabitants arrived, how they fought each other, formed nations, fell out over religion, acquired a large empire, became gradually more democratic, helped win a couple of world wars and were left wondering what to do next. At the end of the book are detailed timelines for each period, which provide useful reference and make fascinating reading in their own right.

So – what did the Romans achieve? How did Christianity arrive? Who are the English and why did they fight the French so often? What is Henry VIII’s greatest legacy? When did democracy start and people get the vote? Why on earth did Britain get involved in WW1?

A Bit About Britain’s History might be the only book on British history you’ll ever need; or it might be your stepping stone to more in-depth academic reading.

A Bit About Britain’s History is available on Amazon, and (of course) Amazon UK.

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