190 | 19 TURING’S mONUmENT
introduction of the bombe, in 1940, was the start of Bletchley Park’s conversion into a code-
breaking factory (see Chapter 12) and by the end of the war there were more than seventy
buildings on the site, including the original mansion and its outbuildings. These structures
supplied the capacity to house more than 3000 people per shift, as well as the large quantities of
machinery and other equipment involved in the codebreaking work.
The codebreakers move out
In April 1946 Britain’s military codebreaking HQ was transferred from Bletchley Park to
Eastcote in suburban London, where the codebreakers took over what was previously an
outstation housing bombes (see Fig. 12.3).^1 They transported as much of their codebreaking
machinery as was needed for their peacetime work, including two of the nine Colossi and two
British Tunny machines (larger replicas of the German cipher machine, used for decoding
broken Tunny messages). At the time of the move, the organization’s old name ‘Government
Code and Cypher School’ was formally changed to ‘Government Communications
Headquarters’ (GCHQ). Six years later another large move began, and during 1952–54
GCHQ transferred its operations away from the London area to a large site in Cheltenham,
the quiet town where it remains to this day.
Burying the whole Bletchley Park operation in secrecy was inevitable. With fresh
conflicts—and the Cold War—just around the corner, GCHQ did not want the world
knowing how good it was at breaking codes. So the documents recounting Bletchley Park’s
wartime story were imprisoned in classified archives, and few had any inkling of the site’s
historical importance. It was not until the 1970s and early 1980s—with the publication of
figure 19.1 Hut 8, where Alan Turing worked on Naval Enigma.
Copyright Shaun Armstrong/mubsta.com. Reproduced with permission of Bletchley Park Trust.