Bletchley Park
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Bletchley Park was once “Britain's best kept secret”. It was here that cryptologists, especially Alan Turing and Gordon Welchman, managed to break the code of Nazi Germany's “Enigma” machine, and later even more complex encryption systems. Eventually this led to the development to the world's first digital electronic computer.
The codebreakers' contribution to the Allied victory in WWII is immense. It is often estimated that their achievements shortened the war by at least two years.
So there are few places in the world of greater and more lasting historical significance.
Yet for decades after the war, none of this was commemorated or even talked about. All former staff of Bletchley Park, sworn to secrecy, did keep shtum about it – after all it was the Cold War now. Only gradually did the secrets come out, from the mid-1970s. Preservation of the site as a memorial began in the early 1990s, i.e. only after the end of the Cold War.
Now the previously derelict historic site has been restored so it looks very similar to what it looked like during the war. Several buildings contain a whole range of museum exhibitions. All together these can keep a visitor busy for days.
More background info: The original Bletchley Park was a country estate with a grand mansion dating back to the 19th century. But in 1938, as war began looming large on the horizon, it was bought up for the Secret Intelligence Service. The site was mainly chosen for its quiet but strategically convenient location within easy reach from London and halfway between Oxford and Cambridge (from whose universities the key personnel was expected to be drafted mainly).
At the beginning of WWII it was still only a relatively small group of experts who worked here, including mathematicians and linguists, but allegedly also chess champions and people who excelled at solving cryptic crossword puzzles.
The key “enemy” of the codebreakers at Bletchley Park at the beginning of the war was the infamous “Enigma” machine, a device used by the Nazi German military to send encrypted messages. Using multiple letter-scrambling wheels called 'rotors' it produced cyphers that were deemed unbreakable. The device could be set to billions of different encryption combinations. It was clear that this system could not be broken by intelligence alone, it also had to be sped up by means of mechanization.
A key figure in developing a machine to do just that was Alan Turing, a pioneer in what would become known as computer sciences. He wasn't the only great mind behind Bletchley Park, but he is usually seen as the key genius that made the difference. However, the contribution by fellow codebreaker and mathematician Gordon Welchman has to be especially acknowledged too.
(Alan Turing, by the way, is famous for a number of other achievements too, e.g. the Turing Machine, an abstract computational model, the Turing Test, to determine artificial intelligence, and seminal work in the field of mathematical biology, especially morphogenesis, for which he predicted/formulated some basic principles even before DNA was discovered.)
The machine that Turing (and others) devised at Bletchley Park to help break the Enigma code was called “Bombe” – why that odd name for the contraption was chosen is somewhat unclear. One speculation is that it came from a Polish expression for 'super'. Polish cryptologists, who had also made significant efforts to crack Enigma, had shared their work with the British. Hence the link.
Exactly how Enigma, the Bombe and the whole process of codebreaking worked cannot be explained here. For one thing it would be way beyond the scope of this website, and certainly this particular chapter, and also because, quite frankly, it's too complicated. So much so that I still haven't properly grasped it all myself. If you really want to know, go to Bletchley Park or ask your favourite maths genius amongst your friends and family.
Suffice it to say here that it was crucial to find the Enigma's start settings, which were changed every day, and that the mechanization of the calculation needed to do that was sped up immensely by the Bombe machine. It wasn't a computer as such, but a kind of giant electro-mechanical calculator with the single purpose of running through all possible Enigma start configurations (in what today is known as a 'brute-force attack' kind of computation).
The input for the machine was based (and dependent) on what was called a “crib” – a stretch of cypher text that the codebreakers could have a good guess at (e.g. because it was of routine stereotypical content, such as “keine besonderen Vorkommnisse” = 'nothing to report').
If the crib and the running of the Bombe succeeded in finding a potential Enigma start setting, this was tested on more texts on yet another machine, and if it was found to be the correct setting it could then be used to tune the British Typex machine so that the intercepted cyphers could be typed in and the output would be plain text in German, which could then be translated and passed on to the relevant points in the military command.
In this manner, Bletchley Park managed to provide substantial intelligence about the movements and plans of the German military. It goes without saying that this resulted in an enormous strategic advantage.
There were setbacks too, though, especially in 1940 when Germany upgraded the navy version of the Enigma to another level of encryption (a fourth 'rotor') and the codebreakers were blacked out for months.
Eventually they managed to crack this next level too, partly thanks to daring secret service operations including the salvaging of a navy Enigma machine from a sinking German submarine!
Given the success of the Bombe machine, it was soon mass produced and whole halls with rows of Bombes were operated, mostly by female staff, who were referred to as Wrens (from the abbreviation WRNS – Women's Royal Navy Service). I suppose today such referring to women staff by the word for a small bird would be deemed politically incorrect ...
It should be pointed out, however, that as the operations at Bletchley Park grew and more and more buildings were constructed, the increase in staff (to about 10,000 at its peak) to run it all also meant that in the end women outnumbered men three to one. And that was not just in “menial” jobs. Women also contributed decisively to the codebreaking as such, and there was apparently a working atmosphere of equality among men and women.
Work was hard for everybody – and round the clock, in three 8-hour shifts. But it wasn't all work, there was also play. This included literally plays, performed by amateur troops made up of Bletchley Park staff, but also concerts and other such entertainment offers. And then there were was also “play” on the personal, private level. There were many romances between staff, several leading to marriages.
But work got more serious too. Germany developed an advanced cypher machine called Lorenz (nicknamed 'Tunny' at Bletchley Park). This fiendishly complex machine was used by the German High Command, including Hitler himself.
To break its code, an even more complex and much faster machine was needed than the Bombe. This led to the development of “Colossus”, a machine that is widely regarded to have been the world's first real programmable electronic digital computer (the same title is, however, also claimed by Konrad Zuse's “Z3” developed in Germany by 1941 – see Deutsches Technikmuseum). “Collossus” was not devised by Alan Turing, though he contributed to the principles of its operation methods, but by an engineer called Tommy Flowers.
Development began in late 1943 and a first version was up and running in February 1944. An improved and much faster version was finished and in operation by 1 June, just before the D-Day Landings of the Allies in Normandy, France. Through the intercepted communications deciphered by Colossus it was confirmed that Hitler and the German High Command had swallowed the Allies' deception plan prior to the landings. This was another strategically vital success of Bletchley Park's codebreakers.
After the war, the secrecy of what had gone on at Beltchely Park was kept up – now in the name of keeping the achievements hidden from the Soviets in the emerging Cold War. The ten units of Colossus machines, as well as the associated documentation files, were destroyed. (The one at the National Museum of Computing is a replica – see below).
Much more tragically, the life of one of the key figures of Bletchley Park, Alan Turing, was also destroyed after the war. Turing was a homosexual. And in 1952 he was prosecuted for “gross indecency” after admitting to having had a sexual relationship with another man. Turing confidently conveyed that he saw nothing wrong with that, but the times and the laws of the day were against him. Back then homosexual acts were still illegal, “criminal” acts in Britain.
Turing was convicted, and to avoid imprisonment he accepted the alternative of “treatment” of his homosexuality, which in effect meant chemical castration. He was also barred from working for GCHQ (Government Communications Headquarters). In 1954 he was found dead as a result of cyanide poisoning. It was presumed suicide, though this conclusion remains controversial to this day.
It wasn't until 2009 that his name was first officially rehabilitated when the Prime Minister issued a formal apology. In 2013 the UK (or technically: the Queen) granted Turing a “Royal Pardon”. But of course that is little compensation for having treated a man in this manner who was, after all, one the true heroes who Britain and the Allies owed so much to and without whom WWII and word history would have taken a different course.
The story of Alan Turing, and in particular his role at Bletchley Park, is the subject of the 2014 movie “The Imitation Game”. This film was partly shot on location at Bletchley Park itself.
The use of the original location had only been possible because meanwhile the historical site had been saved from destruction. After the war the site had first been turned over to other uses, but bit by bit it was largely abandoned and became derelict. Only in 1992 did a group of historians succeed in saving what remained of the site from complete demolition and redevelopment. Only a couple of the blocks built after 1942 had already been demolished, but all of the original structures from the earlier stages of Bletchley Park's development were still there.
Work began to turn the site into a proper memorial, and in 2014 over two decades of work culminated in the opening of the site as it is today, with much of the war-time look of many of the old buildings restored and newly developed exhibitions housed in several of these buildings.
What there is to see: loads! In fact there is so much to see that it is recommended that you spread your visit over two days. Otherwise it gets too much to take in all the information.
If you do decide to be sensible and split the visit, then say so when you first get to the ticket counter – because you can get a free upgrade to an annual pass when you purchase your admission ticket.
Once inside, you are expected to start with the introductory exhibition that is set within the visitor centre – which used to be Bletchley Park's Block C. This into exhibition tells the story of WWII and codebreaking in a very quick overview kind of way, but also offers a few interactive elements that go deeper into details.
Also within the visitor centre there is a cafeteria, a museum shop and, at least at the time I visited, an extra exhibition about Internet security (which I didn't manage to see in the end).
Before you exit Block C and explore the rest of the site you have to decide whether or not to make use of the complimentary audio guide. You don't really need it in the main museum in Block B, but it does enhance things elsewhere. This is what I did: I declined the audio guide on the first day of my visit and used that day to explore only the museum in detail, but left the rest of Bletchley Park for the following day. On that second day I then did use the audio guide – and found it useful. It provides additional information, short videos with interviews and A/B comparisons of historical photos with contemporary ones (you “rub” the new photo away on the touchscreen to reveal the historic one … a bit gimmicky really).
The main museum building is Block B. Outside stands a monument honouring the veterans of Bletchley Park. Inside you can find several separate but interlinked exhibitions. These incorporate the world's largest collection of Enigma machines, a Bombe demonstration model and other technical details, as well as a timeline, period clothes and radios, and lots of text panels trying to explain the finer details of the operations at Bletchley Park. There are also videos, e.g. about the inner workings of the Enigma machine.
First and foremost, however, this is the place where you can attend demonstration sessions in which the rebuilt Bombe machine is presented and museum staff explain how it all works. It is certainly a noisy machine! I can vouch for that, as I heard it even from the other end of the building. But I missed the actual explanations.
Amongst the most noteworthy other exhibits is a sculpture of Alan Turing (hovering over an Enigma machine) made entirely of slate. Alan Turing's teddy bear is a touching artefact too.
Yet while Turing's achievements and his contribution to the British war effort are amply celebrated, the sad story of his life's end, his homosexuality and criminal conviction for it are only mentioned on the side, in a single small panel. At least this dark aspect wasn't completely swept under the rug.
Upstairs is an exhibition about the people of Bletchley Park and this has loads of personal stories, some presented in video format: as interviews with veterans telling how they experienced the place back then. Very captivating!
The adjacent Home Front section illustrates what life was like in general at the time and features, amongst other things, a fully furnished living room and a kitchen. It was all rather small and crammed.
At the back of this floor is an odd addition: a reconstruction of a Nazi German bunker and “Funkraum” (radio room), which looks more like a jumble room full of relics from the time. A display cabinet next to this has loads of Nazi insignia and relics too (plenty of swastikas and SS symbols and the like).
After having spent a good few hours in all of these exhibitions on my first day, I returned the next day to see the rest of this vast complex.
At the heart of it all is the old mansion. It was here where the first small group of codebreakers started to work before purpose-built huts and blocks were gradually added.
Most of the ground floor of the mansion is open to visitors. Some parts have been reconstructed to look exactly as they did back in the day, with office furnishings, documents, typewriters and even mock ashtrays with mock cigarettes not smouldering away (of course back then virtually everybody would have smoked, but today the entire Bletchley Park complex is non-smoking). In the reconstructed office of Commander Alastair Denniston it is a mock pipe instead.
What may have been a ballroom once now houses a special exhibition about the making of the movie “The Imitation Game” (see above). You can watch videos of the cast and crew commenting on the project, and film costumes and props are on display. The most dramatic of these is the model of a Bombe machine (not a working model, unlike the rebuilt Bombe in the Block B museum, but still visually impressive).
Another room had a special exhibition about Gordon Welchman, Bletchley Park's “other” genius (or “forgotten genius”, as it is sometimes put). He went on to work in the USA after WWII where he continued to work in cryptology and intelligence. Interestingly, he apparently predicted that with all this technology developing, society would inevitably end up under far-reaching surveillance. A proto-Snowdon, as it were ...
Behind the mansion you can explore other parts of the old original grounds, such as the so-called cottages (once Turing's workplace at an early stage) as well as the garages. A few veteran cars are on display here.
You can see the original main gate (now closed) and the guardhouse, and back at the front of the mansion take note of the tennis court: somewhere there must be speakers hidden in the trees or bushes, playing typical “pock ... pock … pock” of (invisible) tennis rackets hitting a (non-existing) ball. Nice gimmick. Nearby is the Polish memorial – which honours the important early contributions Polish cryptologists made to breaking Enigma.
Of the set of hastily erected wooden huts that were first built when space in the mansion and cottages ran out, several have been reconstructed to their war-time appearance. Others are still dilapidated. Yet another hut, which would have been the entertainment hut back then, now houses a special exhibition about the archaeological research that was undertaken at Bletchley Park when the site was first made accessible to historians and researchers. It also shows the preservation efforts that have gone into the development of today's memorial site.
Inside the restored original codebreakers' huts is a mix of exhibitions and just reconstructed offices. Projected onto the walls inside the semi-darkened rooms are images of figures in period attire going about their work, talking on the telephone or just having a cup of tea. One of the rooms is Alan Turing's modest office. In another room you can see Typex machines.
Furthermore there is a small cinema room showing a film abut the daring naval operation during which two special agents managed to retrieve an Enigma machine, together with a code book, from an already sinking German U-Boot after its crew had abandoned ship.
Yet others rooms have interactive stations with touchscreens on which you can try your own hand (and mind) at solving some of the riddles the codebreakers were faced with.
Another room here had a special exhibition on a topic only marginally related to Bletchley Park: about carrier pigeons and their role in WWI and WWII communications. Learning what “war heroes” these clever creatures were, you won't look at them and think “vermin” ever again. (Not that I did – I've long been admiring pigeons, especially for their incredible flight abilities and their adaptability, though much less so for the destruction caused by urban feral pigeons and the precaution measures this has necessitated, such as protective netting covering monuments.)
A separate building features a rather more crude reconstruction of the Bombe rooms. Obviously they couldn't have stocked it with a whole row of reconstructed/model Bombes, so instead they have two-dimensional images of them on life-size posters as stand-ins. In between these, video projections are shown in which actresses dressed as Wrens (female Bombe operators – see above) talk about their angle of working at Bletchley Park.
Of the concrete blocks added from 1942 onwards, none are currently open to visitors. Some are occupied by businesses, others are still derelict – but there are plans afoot to incorporate some of these into the memorial at a later stage too.
So this concludes the memorial complex of Bletchley Park as such. However, there is yet one more element also accessible from within the memorial grounds, but run independently from it by volunteers: the National Radio Centre. Unfortunately it was closed at the time of my visit, so I cannot report anything more about it.
Back inside the visitor centre in Block C you can have look around the museum shop. Apart from souvenirs, postcards and the like, it also has a large selection of books – as well as DVDs (including, naturally, copies of “The Imitation Game”).
Occupying the former Block H, the last one to be built at Bletchley Park (in 1944), is the National Museum of Computing. It's outside the Bletchley Park memorial's perimeter and is also run independently from it (and charges its own admission fee). But it is closely related to the same history: it was here that Colossus was built, and the museum has a working replica of it! So it is covered here as well:.
When I arrived I was lucky to catch one of the guided tours by one of the museum's expert wardens/curators. This started in the room in which a replica of a precursor to Colossus was rattling away, and its principles (and problems) were explained.
The highlight, however, is obviously Colossus, the world's first real computer (see under background). It is a huge machine of valves, wires, cables and switchboards and other controls. It's amazingly “antique hi-tech”.
Also fascinating in that way is another early monster of a computer, called WITCH. This one was originally installed in one of Britain's first nuclear power stations, and as the museum warden pointed out, this is actually the world's oldest original computer that's still in working order (not as a rebuilt one like the museum's Colossus).
The rest of the museum has less ancient specimens from different eras of the computer age, but some of these are quite revealing of how much the field has progressed in just a few decades.
On display are e.g. a hard drive with a 4-megabyte capacity that is the size of a cartwheel, or tape memory machines that look more like washing machines than computers. Later models look more familiar, like various PCs. It obviously depends on your age how entertaining you find all this. I am old enough to have been amused even by the sight of a type of pocket calculator we had to use in an 'informatics class' in school ... before there were PCs, let alone smartphones and tablets!
There are also sections about the evolution of virtual reality and computer games, the role of computers in air traffic control, the role of women in the history of computer sciences and finally the display of some former “supercomputers” such as the legendary Cray-1.
Computer geeks, especially more seasoned ones, will obviously get a lot more out of all this than people with less interest in such a specialist branch of technological history. Parts of it were way too specialized for me, but the main parts I found quite impressive.
Location: to the south of Milton Keynes, Buckinghamshire, Great Britain, off Sherwood Drive, just north-west of Bletchley train station. It's some 40 miles (65 km) north of London.
Google maps locators:
Gate and entrance to visitor centre: [51.9974, -0.7392]
National Museum of Computing: [51.9983, -0.7437]
Access and costs: a bit off the usual tourist routes, but not hard to get to; quite expensive, but worth it for what you get.
Details: To get there by car from Milton Keynes head for Bletchley along the B4034 and follow the signposting, or enter this address and post code into your GPS: Sherwood Drive, Bletchley, MK3 6DS (note: the official postal address of the museum would send you the wrong way). There is a large free car park at the site – and more parking can be found further up the drive at the National Museum of Computing.
The site is not very far (ca. 100 yards) from Bletchley railway station, which has connections e.g. to London Euston, Coventry and Birmingham New Street. And what's more, there is currently (spring 2016) a 2-for-1 promotion if you come by rail!
In addition there are numerous buses from various parts of Milton Keynes that go to Bletchley bus station, which is some 300 yards away along Sherwood Drive.
Opening times: daily (except for Christmas and New Years Day) from 9:30 a.m. to 7 p.m. in summer (1 March to 31 October) and to 4 p.m. only in winter. Last admission an hour before closing times (but it would be pretty pointless to come here for just one hour).
Admission: 17.25 GBP, concessions (seniors, students) 15.25 GBP, children 12 to 17 10.25 GBP, family tickets (2 adults, 2 children 12-17) 45 GBP. An upgrade to an annual pass is FREE! For a return visit you'll need your stamped ticket and also an accepted form of ID.
The National Museum of Computing has more variable opening times. The Colossus gallery is normally open daily from 10:30 a.m. to 5 p.m., while the rest of the museum is normally open only on Thursdays, Saturdays and Sunday afternoons (from 12 noon). There are regular guided tours at 2 p.m. on Tuesdays and at 10:30 a.m. on Thursdays. But tours can also be booked for other times. During school holidays the museum's opening times are extended, and there may also be prolonged opening times and extra tours at other times. Check their website (tnmoc.org). So-called Insight Guided Tours can also be pre-booked online. These cost 12.50 GBP (concession 10 GBP).
Admission to the museum as a whole is 7.50 GBP (5 GBP concessions); when only the Colossus gallery is open, entrance to that costs only 3 GBP (2 GBP concessions).
Time required: a lot! And I mean really a LOT! So unless you're happy with just a superficial look, you should consider spreading your visit to Bletchley Park over two days (which could be half days each). There is so much to see and take in that it is hard to do in one single visit – and the fact that you can get a free upgrade to a year pass allowing unlimited return visits really is an incentive.
Combinations with other dark destinations: The closest other one of the sites featured on this website would be IWM Duxford, which is about an hour's drive to the north-east near Cambridge. Similarly accessible is London, but you wouldn't want to drive a car there. Fortunately you could also get there by train.
For anything further afield see under Great Britain in general.
Combinations with non-dark destinations: Bletchley Park is in Milton Keynes. Do I have to say more? For Brits probably not. But in case you don't know: Milton Keynes, a planned “new town”, has the reputation of being one of the most boring towns in Great Britain for a reason. There is no genuine town centre. It's basically just a sprawl of housing and industrial estates, connected by roads planned by someone who really must have had a thing for roundabouts. I've never seen as many in such concentration anywhere else on Earth. (For those who are uncomfortable with roundabouts, this place must be hell on Earth! … for those who like them I guess it's magic ...)
That said though, I did find a rather pleasant spot in the south of Milton Keynes conveniently being the location of a budget hotel. That hotel incorporated a converted historic windmill, so it had its visual charms, and its location right on Caldecotte Lake also had its merits.
But otherwise you'll have to look further afield to find the prettier and more touristy sides of Great Britain. At least some of those are all a similar distance from here (30-50 miles): first and foremost London to the south, but also Oxford to the south-west and Cambridge to the north-east, as well as Stratford-upon-Avon and Birmingham to the north-west.
