Alan Turing’s top secret documents that were used to break the Nazi’s Enigma Code have been found scrunched up in the roof of Hut 6 during a restoration at Bletchley Park.
The stack of papers was used as roof insulation for Hut 6 to block draughty holes, which sheltered the unit that deciphered Germany’s encrypted communications.
Among the papers was the only known copy of “Banbury sheets”, a technique devised by the mathematician to speed up the decrypting process.
"Discovering these pieces of code-breaking ephemera is incredibly exciting and provides yet more insight into how the code breakers worked," said Ian Stander, chief executive of the Bletchley Park Trust.
"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."
Alan Turing was a Cambridge mathematician, cryptanalyst and pioneering computer scientist who spearheaded the Enigma code-breaking operation during World War II and was later persecuted by the British government for his homosexuality.
The documents have been found during a multi-million renovation of the site in 2013 and were frozen to prevent further deterioration, according to a report.
The cache of papers will be on display as part of the exhibition called The Restoration of Bletchley Park.