Alan Turing’s Code-Breaking Papers Discovered Stuffed In Roof Holes At Bletchley Park

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Justine Alford

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911 Alan Turing’s Code-Breaking Papers Discovered Stuffed In Roof Holes At Bletchley Park
Bletchley Park Trust

During the Second World War, mathematician Alan Turing devised several techniques for cracking the codes of the German Enigma machines, allowing Allied forces to intercept encrypted Nazi messages. Although the code-breaking work of Turing and his colleagues helped the Allies win numerous critical Nazi engagements, their work remained a secret for decades and all documentary evidence from the process was destroyed under strict wartime rules. Or so we thought.

Unnoticed for some 70 years, a sample of Turing’s top-secret documents has just been discovered at Bletchley Park, Britain’s code-breaking center. The papers were found in Turing’s workplace, Hut 6, but in a rather peculiar location: stuffed inside holes in the ceiling. Apparently, the team had used them as draught excluders to keep out the cold.


Bletchley Park Trust

As reported by The Times, the notes were revealed during a multi-million pound restoration project of the site in Milton Keynes, Buckinghamshire. They were actually discovered back in 2013, but images have only just been released to the public. Among the findings in Hut 6 were parts of an Atlas, a pinboard and a fashion article from a magazine, according to the Bletchley Park Trust. The artifacts will be displayed as part of a new exhibition called “The Restoration of Historic Bletchley Park,” which will provide a snapshot of the kind of work that was carried out at this once secret intelligence and computers headquarters.

Although all of the notes, scribbles and crossings out are interesting, perhaps the most striking find was the only known example of so-called “Banbury sheets,” papers punched with holes which were slid past one another to allow comparison of enciphered texts. These demonstrate Turing’s Banburismus process which was developed to speed up the decryption of Nazi messages. Alongside this intriguing find is a bunch of handwritten notes that have yet to be identified.

Bletchley Park Trust, via CNET


“Nobody seems to be able to work out what they are - we’ve sent things off to GCHQ [UK Government Code and Cypher School HQ] - and there are a number of items that we’ve yet to understand properly,” Bletchley Park’s Director of Learning and Collections, Victoria Worpole, said in a news release. “We’re unveiling a mystery.”

According to Business Insider, as soon as the papers were discovered, they were frozen to prevent any further damage and then cleaned. Conservators have also been working on repairing the documents and ensuring that that they remain well-preserved.

“Discovering these pieces of code-breaking ephemera is incredibly exciting and provides yet more insight into how codebreakers worked,” Bletchley Park Trust chief executive, Iain Stander, said in a statement. “The fact that these papers were used to block draughty holes in the primitive hut walls reminds us of the rudimentary conditions under which these extraordinary people were working.”

[Via The Times, Business Insider, The Register and BBC News]


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  • World War II