Top secret documents that were used by codebreakers during the Second World War have been discovered stuffed in the walls of a hut at Bletchley Park.
The papers, relating to a method devised by Alan Turing and used to crack the Enigma code, were found in an out-building at the heritage site during restoration work.
The documents are the only known examples of Banbury sheets, part of an improbably crude technique involving hole-punching and light that was used to decipher Nazi messages.
Instead of destroying the papers after use as they were supposed to, codebreakers in Hut 6 appear to have jammed them into the ceiling and holes in the walls in order to block the draft.
Bletchley Park’s Director of Learning and Collections, Victoria Worpole, said: "It’s quite rare for us to find new paperwork because any that survived is in either our archive, at GCHQ or the National Archive, so to find actual materials that were used by the codebreakers, shoved between beams and cracks in the woodwork is really exciting.
"We’ve had a conservator work on the materials to make sure we preserve them as best we can.
"It’s quite interesting to think that these were actual handwritten pieces of codebreaking, workings out."
During restoration work in Hut 6, renovators also discovered parts of an Atlas, a pinboard and a fashion article from a magazine.
Find out more about codebreaking during the Second World War at bletchleypark.org.uk
