The BBC reports that the British archive of secret codes is soon to be made public:

More than a million documents from Bletchley Park, Britain’s wartime code decryption hub, are to be digitised and put online. The project will take several years. What follows are some examples of the documents in the archive.

Work in progress. This shows an analyst’s workings as they decipher an intercepted encoded message. The next stage was to enter these codes into the mechanical devices developed at Bletchley Park to produce the final decoded message.

More information can be found here:

…the archive is so big nobody knows exactly what each individual document stored there contains.

However, the information they expect to dig out will definitely include communication transcripts, communiques, memoranda, photographs, maps and other material relating to key events that took place during the war.

The BBC says HP is subsidizing the conversion to digital and started the project when they heard Bletchley Park was in financial trouble.