Bletchley Park beyond Enigma

Last updated on August 23rd, 2023 at 11:37 am

Bletchley Park, enigma, ultraPart 2 – Lorenz and legacy

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 pored 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.  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.

Codebreakers, Station XOf 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.

Bill TutteBreaking 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 and had their own intelligence successes.  Further, Peter Caddick-Adams writes in ‘Sand & Steel’ (Amazon link) that Bletchley Park’s one weakness was that it was only able to intercept radio messages and many German agencies in Western Europe relied on landlines.  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 decisive 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 the remarkable Operation Fortitude which convinced Hitler (against the advice of his generals) that the expected Allied attack in North West Europe would be made on the Pas-de-Calais area of France, and that Normandy was a diversion.

Bletchley ParkIn 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.

Alan Turing's officeThe 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.

Alastair Denniston, officeIn 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 too.  There were also, it must be said, some mutually disparaging opinions 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 by the end of the war had achieved an extraordinary level of closeness.  US cryptographers served at Bletchley and bombes (improved ones) were built and used in the US.

Faces of Station X, Bletchley ParkBletchley ParkOne 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 – 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.  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.

Alan Turing’s childhood teddy bear, Bletchley ParkFrom 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.

Bletchley ParkFurther reading and information:

The Bletchley Park website
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.

There are seemingly countless documentaries on YouTube about Bletchley Park; quality varies.

Both GCHQ and NSA websites contain some interesting information and there is a fascinating website based in the Netherlands dedicated to cryptography, the Crypto Museum, which also includes the history.

There is no shortage of traditional reading material on Bletchley Park.  I used ‘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). Links are to Amazon.


52 thoughts on “Bletchley Park beyond Enigma”

  1. Just when you think you know a bit about Bletchley Park, someone tells you something else.

    Did you ever listen to Hut 33 on Radio 4? It wasn’t one of their best comedies, but it was amusing.

  2. I have found another reference to Bletchley Park in my reading. I was doing a little research on Agatha Christie and her work during both World Wars recently and discovered that she had been investigated by MI5 in 1941/2. She wrote a spy thriller called ‘N or M?’ and her ‘baddie’ is called Major Bletchley. MI5 naturally thought she had a spy working for her at Bletchley Park. Apparently, she decided on the name after spending ages stuck on a train just outside Bletchley, whilst travelling to (or from?) Oxford. She knew Dilly Knox and this is the explanation she gave him.

  3. Fascinating, Mike. I really loved part one, too — a remarkable period in history and it looks as though it is beautiful re-created. I think this may be on my itinerary this fall!

      1. Always long. Aiming to hit London-area in September, then maybe train to York, Bath again, who knows where. We’ve got to lock in accommodations and dates but eager to get back!

  4. Very interesting Mike, you’re a very good writer. I remember reading a lot of it when I visited, but it was a few years ago so your excellent post has reminded me. I particularly remember reading about Dilly Knox and Tommy Flowers. My first job on leaving school was as a telephonist with the then GPO. I’m glad the house wasn’t demolished, it’s such an interesting part of our history.

  5. Hi Mike – there’s an awful lot there to absorb and take in, and where one can get a flavour of the physical aspects of the time … it’s so well worth a visit and I need to go again. Cheers and thanks for the detailed information you’ve given us – Hilary

  6. This is very interesting. I could not figure out why I had some idea of Bletchley Park’s role in WWII. Since you mentioned it, I;m sure it had something to do with it being opened as a museum a few years ago.

  7. Fascinating as always. Thank God for minds like these! And I am thankful also for the local historians who were able to save Bletchley Park.

  8. A marvellous, fascinating set of further information on such an intriguing project. Thank goodness for those who rescued the museum from the bulldozers of the Philistines. Well done

  9. Fascinating post! I’m thrilled that these historical places are being properly preserved and you can take a virtual step back in time by visiting them. I’ve read some very good books about codebreaking during WWII. If you haven’t already read if, I highly recommend “Between Silk and Cyanide” by Leo Marks.

  10. artandarchitecturemainly

    Thank goodness that Bletchley Park itself was not destroyed by historically insensitive thugs and was saved by historians in 1992. In 2014, it was officially opened as a really important visitor attraction so that those of us born straight after WW2 ended will find as much kept as possible.

  11. Oooooooh gosh I’m getting so excited for my upcoming visit there, thanks to these awesome posts. Also, Max Hastings happens to be one of my favorite WWII authors – I immensely enjoyed the Secret War. I’m glad I will have that knowledge going in for my visit!

    1. artandarchitecturemainly

      Turing rightfully receives the kudos now, but soon after the war Turing was charged with a crime (homosexuality), gaoled and chemically castrated by a nasty legal system 🙁 He died very young 🙁

  12. We have enjoyed your posts a great deal, please keep it up! Bletchley Park will definitely be on our list of places to visit if we ever make it to Britain again! Just one thing, a typo alert. You used “poured” for “pored” at one point. It’s not a big deal, but I thought I’d mention it.

  13. Thank you for another fascinating blog post. I love that “an unknown but exceptional electronics engineer working for the GPO…(named) Tommy Flowers…designed the world’s first practical electronic information processing machine – a computer.” What a wonderful name and what a significant accomplishment! I also like that there were music, dancing, and theater activities at Bletchley Park. I recently learned while walking with a friend whose mother is British that HER mother (my friend’s grandmother) shared with her extended family a year or two before her death that she had become pregnant during WWII due to a romance with a US military officer while her own husband was missing during the war (it turned out he had been a prisoner of war for over three years…) She was able to leave her town along the east coast of England, claiming mental distress, and travel to Cornwall, where she bore her child and gave her up for adoption. My friend’s grandmother was able to keep this war-time relationship and pregnancy a secret from her entire family — including her husband, who eventually was rescued and returned to Britain — until she was in her eighties. So much history! So many stories! I look forward to reading more of your posts in 2020.

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