Code of honour | The Intelligence Factory, Bletchley Park, Buckinghamshire

A century ago, Bletchley Park in Buckinghamshire was a large country estate owned by the Leon family. Sir Herbert Leon was a financier and Liberal politician who acquired the Victorian neo-gothic pile as a family home. He died in 1926 and his wife 11 years later, at which point his two grown-up children decided to sell the estate. This was at the time in the late 1930s when the government was looking at properties outside London to evacuate key operations if war should come.

Bletchley Park was ideal: available, a quiet rural spot, yet easily reached by rail from London, Oxford and Cambridge. It also had access to communication cables running alongside the nearby A5 main road. Admiral Hugh Sinclair, head of the Secret Intelligence Service, bought Bletchley Park. Over the next eight years, the site would be transformed into the secret headquarters of Britain’s wartime signals intelligence operations.

On 4 September 1939, the day after war was declared, about 180 people were working at Bletchley, including newly recruited mathematicians Alan Turing and Gordon Welchman. By early 1942 Bletchley Park had developed from a small community of specialist cryptanalysts into a vast and complex global signal intelligence factory. It hit its peak in early 1945 when about 9,000 people worked at Bletchley Park and its associated outstations.

Military historian Richard Holmes, who died in 2011, said that the work at Bletchley Park “was utterly fundamental to the survival of Britain” in the second world war. “I’m not actually sure that I can think of very many other places where I could say something as unequivocal as that. This is sacred ground. If this isn’t worth preserving, what is?”

“BP” as everyone posted here called it, grew from a small team of specialists to a vast installation facility of thousands of dedicated women and men. The extreme combination of determined people with cutting-edge technology came together against all odds to win the war of national survival. In tough conditions they provided vital intelligence and developed pioneering technology that had a direct and profound influence on the outcome of the war. Codebreakers remained tight lipped about their role because they had sworn to do so.

In on the secret

The level of secrecy the codebreakers worked under is often difficult to imagine in the information age we live today. Bletchley Park provided the Allies with an unprecedented wealth of intelligence on the enemy’s movements and plans. The intelligence was given the codename “Ultra”, and only top commanders were privileged to receive it. The need-to-know principle was paramount, even at Bletchley Park itself. Few staff knew the whole story and even which other sections existed beside their own, much less what they all did.

Through objects, personal stories and immersive interactive installations, Intelligence Factory, the new permanent exhibition, shows how Bletchley Park operated at its peak in 1945. The production of intelligence was highly mechanised, with thousands of people involved, each responsible for a tiny part of the process. A stark contrast to the portrayal of the few celebrity codebreakers depicted in the film the Imitation Game. 

The display has a huge infographic to underline the scale of the operation. It was a 24-hour set-up and by the end of the war nearly 75% of the staff were women, many aged between 17 and 19. None of them lived on site and all were accommodated in the local area. Recent evaluation of the new exhibition shows that visitors are fascinated by the scale and complexity of handling the vast quantities of information and recruiting, feeding and housing thousands of staff.

There is a wonderful celebration here of people as well as advancing technology, which could be very boring but is actually fascinating. The gulf in scale between the 1940s and today is well represented by the machines used at Bletchley. The 001 Hollerith card puncher and the IBM Model 80 card sorter both feature in the new displays and were part of an army of machines at Bletchley that processed at most 32GB of data during the entire war – an amount that would easily fit several times on a modern smartphone.

There was so much paper. It was management by memo, and a wall of yellowing documents shows the everyday reality of life at Bletchley Park from major issues to petty frustrations, all of which whizzed around the offices via pneumatic tubes. Every scrap of information about the enemy was collected and stored on index cards in wall to ceiling cabinets and boxes.

People power over machines

But it is the people rather than the machines and paper that set the tone at Bletchley. The displays imaginatively weave in personal memories of Bletchley veterans, adding depth and humour to the displays. As Betty Balfour, a wartime codebreaker, observed: “We learned very quickly to ask nothing, do as you are told, do the job. It was boring in the extreme… we enjoyed it because we were with other people.”

And Barbara Smiley, also a codebreaker, said: “We had all signed the Official Secrets Act and were warned against telling anyone, even our families. After asking the first time, my family and friends didn’t ask again.”

The tiny office rooms used for some of the displays could have been a challenge, but each one is used for a single piece of testimony, which has great impact. Some veterans recalled that it was like working underground when the backout blinds were drawn – and that atmosphere of claustrophobic and intense working conditions is well created.

There are few photographs of the interiors of Bletchley Park and all the rooms have been reconstructed from personal memories and by piecing evidence together from archives. Some areas of the work are still secret today. Using the collections, some of which are owned by GCHQ (Government Communications Headquarters), the displays take a thematic approach, looking at intercepting messages, plotting enemy movements and gathering data. But the focus of the narrative is on the people who undertook the work and the complexity of running and supporting such an operation.

The contemporary relevance of gathering intelligence is a clever thread running through the displays – from encrypted burner phones used by criminals, intelligence sent back to GCHQ from Camp Bastion in Afghanistan, modern tracking of naval vessels, and use of computers to hunt for patterns and hidden connections.

The exhibition is bookended by two impressive video presentations – one at the beginning, introducing Bletchley in 1942 and, unusually, one at the end looking at how much Bletchley had developed and changed by 1945, to become the world’s largest intelligence factory.

Remarkably, the displays were prepared largely during the Covid-19 lockdown on Microsoft Teams, and we all know how difficult it is to have creative meetings virtually. The exhibition is a masterclass of storytelling and planning – clear narrative, simple text, effective use of objects, graphics, interactives and digital media and one that all curators planning a major exhibition should visit.

Oliver Green is an independent curator and historian