British Government Places Export Ban on Alan Turing’s World War II-Era Notebooks

The British government has placed an export ban on a small collection of unpublished papers belonging to Alan Turing, the mathematician and computer scientist famous for helping the Allies decode Nazi communications during World War II.

The papers contain Turing’s notes related to the Delilah project, a lesser-known endeavor to develop a portable voice encryption system. Dating to the mid-1940s, the notes “offer unique insights” into Turing’s mind, as arts minister Chris Bryant says in a statement from the British government.

Under the new ban, the notes cannot leave the country—at least for now. U.K. institutions will have until November 15 to purchase the collection. After the deadline, international buyers will be allowed to place bids, per Artnet’s Tim Brinkhof.

“The British mathematician was central to the development of our modern digital world,” Bryant adds. “It is right that a U.K. buyer has the opportunity to purchase these papers to give people the opportunity to continue to study and appreciate his work as an important part of our national story.”

The collection includes two bound notebooks and six batches of loose sheets. While working on the Delilah project, Turing and his colleague Donald Bayley scribbled their thoughts and calculations down in blue ink. The notes have an estimated value of more than $500,000.

Examples of Turing’s unpublished notes are quite rare, as the lauded mathematician did not typically keep his research drafts or letters. In 2015, another set of Turing’s notes sold for over $1 million at Bonhams in New York.

Turing worked on the Delilah machine from Hanslope Park, an estate in Buckinghamshire, England. The portable device encrypted sensitive communications by overlaying noise onto audio recordings. Anybody who intercepted such messages would not be able to understand them, but the intended recipients would be able to filter out the noise using another Delilah machine.

By the time the device was finished, the war had come to an end. Around that time, Turing gave a presentation on the new technology, which he demonstrated using a Winston Churchill speech.

Today, Turing’s inventions are seen as early forms of technologies that would continue to advance many years after his lifetime. 

“I suspect you can trace a timeline directly back to what was happening [at Hanslope Park] 70 or 80 years ago,” Turing’s nephew, Dermot Turing, told BBC News’ Gordon Corera in 2023. “The need for secure communications hasn't gone away.”

The mathematician’s legacy has endured. He was played by Benedict Cumberbatch in The Imitation Game in 2014, and his face has been featured on the British £50 note since 2021. Earlier this year, the University of Cambridge’s King’s College unveiled an abstract sculpture celebrating Turing, who studied math there in the 1930s.

“The United Kingdom owes a debt of gratitude to Alan Turing,” says Andrew Hochhauser, chair of Britain's Reviewing Committee on the Export of Works of Art and Objects of Cultural Interest, in the statement. He adds that the mathematician’s better-known work on the Enigma project “played a major part in winning World War II and saved so many lives.”

Julia Binswanger | READ MORE

Julia Binswanger is a freelance arts and culture reporter based in Chicago. Her work has been featured in WBEZ, Chicago magazine, Rebellious magazine and PC magazine.