Special documentation systems at the Government Code and Cypher School, Bletchley park, during the Second World War

Abstract

The work of GCCS at BP has received much attention in recent years. Concentration, however, has been on the capture of Sigint by the interception services and the problems of decryption of messages in Enigma. Less attention has been placed on the documentation of the decrypts and the intelligence held by the factual indexes maintained by the Air, Military and Naval Sections. Lying behind these were the highly specialized devices which facilitated the translation and analysis of decrypted messages by providing the expansions of abbreviations common in all Sigint and the ‘equivalents’ of German and other terms. This paper describes the work of two specialist units, serving Hut 3 (Air and Military intelligence) and Hut 4 (Naval intelligence), engaged in the creation and maintenance of such devices.