Cracking the code

We have been meaning to visit Bletchley Park for some time, our desire to do so increased by seeing ‘The Imitation Game’ a few years ago, and finally we went – and immediately decided to return soon! There is so much to see here, and luckily entrance tickets are valid for a year, so a repeat visit makes even more sense.

Background history

In 1938 the mansion of Bletchley Park in Buckinghamshire became the base for a small group of people from MI6 and the Government Code and Cypher School. Tensions in Europe were growing, and their job was to set up and run intelligence activity from the house, chosen for its location near to, but not in, London. When tensions seemed to ease the base was closed down, but reopened when war broke out. The work that was undertaken here became vital to the Allied war effort, with ground-breaking inventions which shaped the future of computing science – a perfect illustration of the old adage about necessity being the mother of invention!

Today this site is rightly regarded as a hugely significant part of the history of Britain’s role in World War Two, but it might not have been. In the early 1990s there were plans to demolish Bletchley Park and build housing here, as part of the ever-growing new town of Milton Keynes on whose southern fringes it now lies. After public outcry and campaigning Milton Keynes Council was persuaded to declare most of Bletchley Park a conservation area. The Bletchley Park Trust was formed and in 1994 opened the site to the public as a museum. With financial support from the Heritage Lottery Fund, and from commercial and private sponsors, the museum has gradually grown to become a major attraction – and is continuing to expand and develop additional parts of the site.

Introductory displays

As soon as we arrived, parked the car and started to walk towards the building housing the entrance and visitors centre we were left in doubt where we were, as the stylish signage echoes the coding theme.

We exchanged our pre-purchased online tickets for actual paper ones at the desk and were given a map of the site. The obvious place to start was with the exhibits in the visitor centre, where we watched a short introductory film tells the story of the part played during WW2 by those working at Bletchley Park. There was one of the famous German Enigma machines in a display case (we were to learn much more about these during the course of our visit) and an overview of the processes followed in deciphering enemy messages.

The Enigma machines used a system of rotors to scramble the 26 letters of the alphabet. Its settings were changed daily, based on secret key lists, while some other settings were changed for each message. The receiving station needed to know and use the exact settings employed by the transmitting station to successfully decrypt a message. Much of the work at Bletchley Park focused on identifying the encryption settings each day in order to decipher and translate the messages sent by the German army, air-force and navy.

After exploring these displays, we took a break over a coffee in the café here and studied the map we had been given. It was already clear that we couldn’t see everything on this first visit so we determined our priorities and set off to look around.

The lake

Walking around the small lake in the centre of Bletchley Park you can get a good overview of the layout and see how a family estate was transformed into a top-secret base. The mansion lies across the water, looking every bit the small-scale stately home it once was, but scattered on either side are the many huts, wooden and brick, that were built to house the various operations – first just a couple, then growing in number as the war progressed and the work carried out here became ever more critical to the war effort.

Information boards at intervals describe daily life for the staff working here – the hardships (long shifts, spartan conditions (especially in the winter months) and the impossibility of telling anyone, even close family, what you were doing) – but also the small pleasures of games of tennis, skating on the lake in winter, forming friendships and romances.

The Mansion

The ground floor of the Mansion, as the old house at the heart of the estate is known, is open to visitors and has a number of rooms of interest. We were welcomed on entering by a docent who told us that photography was allowed, if not for commercial purposes, and recommended that we look up at the ceilings as they are quite varied and attractive – he was right!

The office of Commander Alastair Denniston, head of the British Government Code and Cypher School (known as GC&CS), has been recreated in great detail in the Mansion, and was our first taste of the way in which the atmosphere of those war years has been so effectively captured here. In-trays are full, piles of papers lie on the desks, pencils at the ready, typewriters with sheets inserted. On the notice board are announcements of a dance and a concert (social activities were seen as very important in keeping morale high), and a reminder to ‘carry your identity card always’.

A sign describes a historic meeting which took place in this room in February 1941, which it credits as ‘the beginning of the United Kingdom / United States special relationship’. Four US military personnel came to Bletchley Park to discuss an exchange of information on Japanese and German codes and cyphers. This was some months before the US was to enter the war, following the bombing of Pearl Harbor. Even those working here were unaware of the visit, apart from Dennison, his senior team and his personal assistant, recruited to the meeting to ‘pour glasses of sherry’.

The library at the other end of the hallway is similarly recreated to show as it would have looked when in use as a Naval Intelligence office. There are cigarette stubs in the ashtrays and empty, coffee-stained cups beside them. Hats and coats hang on the coat-stand and a cardigan is draped over the back of a chair with a handbag carelessly left on its seat. As elsewhere, the re-creation is based on old photographs and accounts of those who once worked here.

Other rooms in the Mansion are used for exhibitions, one of which is devoted to the Roll of Honour which lists all those believed to have worked in signals intelligence during World War Two, both at Bletchley Park and at other locations. There are photos of a few of them, sound recordings of the memories of just a handful, and an online resource which relatives can use to search for information on ancestors who worked here.

There was also a special temporary exhibition on the work of one of the most significant of the codebreakers, Bill Tutte, whose research in the field of graph theory was of enormous importance in the development of the techniques used here. I have to say though that the explanations of his work and its application to codebreaking were well over my head! I therefore quote Wikipedia on the significance of his achievements:
‘During the Second World War, he made a brilliant and fundamental advance in cryptanalysis of the Lorenz cipher, a major Nazi German cipher system which was used for top-secret communications within the Wehrmacht High Command. The high-level, strategic nature of the intelligence obtained from Tutte's crucial breakthrough, in the bulk decrypting of Lorenz-enciphered messages specifically, contributed greatly, and perhaps even decisively, to the defeat of Nazi Germany.’

The garages

Behind the Mansion are the garages in what was once the stable block, which house several interesting vehicles. They include a Sunbeam Tourer used in the 2001 film ‘Enigma’ starring Kate Winslet and Dougray Scott, which we hadn’t seen but which sounds interesting – I plan to look out for it.

There is also a 1938 Austin Ambulance, used for the same film and also for the TV series ‘Goodnight Mr Tom’, which I have seen. It tells the story of a young evacuee and stars John Thaw. Both vehicles were donated to Bletchley Park by the film company, owned by Mick Jagger, which made ‘Enigma’.

The cottages

Next to the garages is a row of cottages around a stable-yard, presumably built to house staff when this was still a family estate. These were the location for some of the early codebreaking successes, before the various huts were built to accommodate the fast-growing operations here. It was in these cottages that Enigma was first cracked by an all-British team including Dilly Knox, Mavis Lever and Alan Turing. They aren't open to the public - I got the impression that they are in use as private residences.

Hut 3

The highlights of our visit for me were the codebreaking huts, numbered 3 and 6. In these huts Enigma messages sent by the German Army and Air Force were decrypted, translated and analysed for vital intelligence. They have been brilliantly restored and presented in a fashion that recreates the war-time atmosphere, bringing to life the world of the codebreakers in a way that makes the huts seem almost haunted by them. The rooms are ‘dressed’ to resemble what they once were when the codebreakers worked there, and as you enter each you can hear the voices of actors engaged in realistic conversations about their work, and also their off-duty lives. In some rooms there are also projections of actors on the walls, but I think I found those where there was only audio the most effective of all.

A sign as you enter Hut 3 explains:
‘You are now standing in one of the most secret areas of BP where deciphered messages were translated and analysed. Early on in the war the resulting intelligence was sent to MI6 and a limited number of senior army and RAF personnel. The evocative sights and sounds will help you to imagine what happened here. The scenes are set in 1940-41, and are based on the words and memories of BP veterans.’

One of the larger rooms is that which housed the Watch, where a sign explains:
‘Work at BP went on round the clock. In this room there were four Watchkeepers on each shift, led by Watch 1. Most were civilian experts on German, able to fill any gaps in the deciphered messages before translating them. As they had no military experience, special Military Advisers helped compile the final reports.’

Hut 6

This was perhaps the beating heart of Bletchley Park. According to its sign,
‘Some of the most important codebreaking of the war took place in this hut. Little survives to tell us what it looked like inside, but the hut itself remains a witness to those tense times. Images, props, sounds and words are based on Veterans’ recollections and photographs taken later in WW2. They help to conjure up events here on just one date – 28 February 1941 – the day a crucial enemy cipher was broken.’

To capture the sound, as well the images, of this hut I shot some bits of video in a few of the rooms, which I later edited together:

We took a break at this point to eat a light lunch in Hut 4 which was formerly a WW2 naval intelligence codebreaking hut, but which now houses the café. Then we continued our explorations in another of the restored huts.

Hut 8

While the work in Huts 3 and 6 was focused on German army and air-force messages, Hut 8 was devoted to cracking the even tougher to decode naval messages. It was here that the famous Alan Turing did his most famous work, concentrating on this more complex Naval Enigma because ‘no one else was doing anything about it and I could have it to myself.’ Turing devised a number of techniques to speed up the breaking of German ciphers, including improvements to the pre-war Polish Bombe method, which used a machine (a forerunner of today’s computers) to work out the settings for the Enigma machine. This work ultimately enabled the Allies to defeat the Nazis in many crucial engagements, including the Battle of the Atlantic, and in so doing helped to win, and to shorten, the war. His office in Hut 8 has been recreated exactly as it would have looked in World War Two.

Other parts of this hut are devoted to hand-on ‘experiments’ illustrating ideas about probability and chance, and explaining how these are critical to an understanding of codebreaking. The codebreakers looked for what they called ‘cribs’ – predictable repeated phrases (e.g. weather reports) which could give a clue to the day’s encryption settings.

Huts 11 and 11A

Our final stop for the day was in the huts which housed the Bombe machines, developed by Alan Turing from some earlier Polish ones which had been shared with the Allies at the outbreak of war. The machines featured multiple drums representing the rotors of an Enigma machine, which could whizz through all the different possible permutations for the settings each day. Hundreds of these machines were operated by Wrens, here and in outstations in other parts of the country. It was boring and oppressive work, with the women running the machines during long shifts in dark, stuffy rooms, as the displays here make clear.

By now though the museum was getting busier, including with several school groups, and it was harder both to study the displays and to take photos. We found it difficult to follow the detailed explanations of the technology behind the Bombes, so decided in the end to leave this section and the other remaining buildings until the future visit we had already determined to make.

But if you can’t wait till then to find out more about the Bombes, check out the museum’s website’s description of its Bombe Breakthrough exhibits.