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Ordnance survey map of HUT 6 AT BLETCHLEY PARK
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Statutory Address:

The building or site itself may lie within the boundary of more than one authority.

Milton Keynes (Unitary Authority)
West Bletchley
National Grid Reference:
SP 86459 33971


721/0/10020 BLETCHLEY PARK 28-SEP-05 Hut 6 at Bletchley Park

GV II BUILDING: Wooden hut c.150m north-east of the Mansion.

DATE: January 1940

ARCHITECT: Ministry of Works for Government Code and Cipher School.

PLAN: Rectangular, about 65 feet long. Stands immediately north of, and on line with, Hut 1 and parallel with Hut 3.

EXTERIOR: Hut 6 has approximately eleven, irregularly fenestrated, bays, and is built with a brick plinth supporting a light timber frame clad with timber cladding. The repair in the cladding on the west side of the third bay: this marks the position of a `tunnel' used to pass messages between Huts 3 and 6 using a tray on a piece of string pushed by a broom handle. Gutters and downspouts are of asbestos cement. The double-pitch roof is felt covered. There are three entrances: to the gable ends, and south of centre on the west side of the building.

INTERIORS: From the side door a short corridor leads to the main north-south central corridor. Small, roughly square rooms lie off either side of the corridor (nine on the east side). Electrical switches, ceiling light fittings, and possibly radiators may date from 1943 when the building was refitted. Bathrooms and lavarories occupy rooms in the southern part of the west side of the building.

SUBSIDIARY FEATURES: The remains of a brick blast wall run around the south-west corner of the building, which was unprotected by other buildings.

HISTORY: In 1939 Bletchley Park became a dispersal home to the Foreign Office's Government Code and Cipher School. It became the focal point of inter-service intelligence activities, the place where German codes (notably those encrypted using the Enigma machine) were deciphered, the significance of decrypts assessed, and intelligence passed to appropriate ministries and commands. Bletchley Park has become celebrated for its contribution to the Allied victory, as well as for its contribution to the development of information technology. As the organisation enlarged new buildings had to be provided, firstly wooden huts and, from 1942, more permanent brick blocks.

The section which occupied Hut 6 from early 1940 until February 1943 was established by Gordan Welchman at the beginning of the war to decipher German raw Enigma traffic - army and air force messages received by teleprinter or despatch rider from intercept stations. It comprised the following main departments which played a crucial part in the functionaing of Bletchley Park: 1 Registration Room - continuous traffic analysis of Enigma messages 2 Intercept Control - kept in continuous contact with intercept stations 3 Machine Room 4 Sheet Stacking Room - based at first on punched cards, superseded in September 1940 by `cillies' and bombes 5 Crib Room - prepared cribs for bombes 6 Decoding Room - equipped with modified Typex cipher machines for decoding Enigma traffic

In February 1943 the Hut 6 section moved to Block D. By early March Hut 6 had been repartitioned for ISK, a section which worked on Abwehr (German Secret Service) hand ciphers, and renumbered Hut 16. That autumn ISK moved to Block G and the hut was again remodelled, this time to accommodate an overflow from the Naval Section. In the 1970s and 1980s it was used as hostel accommodation, and was probably later used as offices by BT.

SUMMARY OF IMPORTANCE: Hut 6's significance is primarily historic. From early in 1940, soon after GCCS was set up at Bletchley Park, the hut was an important component of the operation, which is renowned for its part in the breaking of the German Enigma code, and in contributing to the Allied victory (especially in the Battle of the Atlantic). The decryption of intercepted Enigma signals by the team housed in Hut 6 was central to these successes, especially in the first part of the war. With Huts 1 and 3 it forms part of a notable group of huts representing the first phase of Bletchley Park's expansion, and externally while unprepossessing its wartime appearance is largely unaltered. Internally too the survival of its wartime layout and character is relatively good. Comparison of a small scale plan of 1943 with the present building suggests that the central corridor was part of the original building, while at least some of the present rooms/room divisions were present in 1943 - although whether they were present in 1940-early 1943 is unknown. This recommendation is informed by considerable English Heritage research, cited below.

SOURCES: English Heritage, Bletchley Park (Architectural Investigations Reports and Papers B/010/2004), vol. 1, 26-38, 246-52; Feilden & Mawson, Bletchley Park Conservation Management Plan (draft 05, December 2004)


The contents of this record have been generated from a legacy data system.

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This building is listed under the Planning (Listed Buildings and Conservation Areas) Act 1990 as amended for its special architectural or historic interest.

End of official listing

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