Bletchley Park Tour

Hut 4

Teamed with Hut 8, Hut 4 was responsible for translation and analysis of naval decrypts and retransmission to the Admiralty. Intelligence Analysis in Huts 3 and 4 was organised into three sections: the Watch, the Advisers and the Index.

The Watch took the decyphered output - in five-letter groups, as it had been intercepted - and regrouped it into German words ready for translation. The translation was performed by German language experts, checked by the Head of the Watch, and passed to Assessors for analysis of its possible information content and priority.

The Advisers paraphrased the message to conceal the original German message, and hence its source. They also used the Index to add any other information which might clarify the message. Any comments were inserted in round brackets to make it clear that it was an inference not contained in the original.

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