Hut 6 at Bletchley Park

Hut 6 at Bletchley Park

A wooden hut built in January 1940 by the Ministry of Works for the Government Code and Cipher School, located approximately 150 metres north-east of the Mansion at Bletchley Park.

The building is rectangular, about 65 feet long, and stands immediately north of and on line with Hut 1, parallel with Hut 3. It has a brick plinth supporting a light timber frame clad with timber boarding, with approximately eleven irregularly fenestrated bays. On the west side of the third bay there is a repair in the cladding marking 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. The gutters and downspouts are of asbestos cement. The double-pitch roof is felt covered. Three entrances serve the building: two to the gable ends and one south of centre on the west side. The remains of a brick blast wall run around the south-west corner, which was unprotected by other buildings.

The interior is accessed from the side door via a short corridor leading to the main north-south central corridor. Small, roughly square rooms lie off either side, with nine on the east side. Bathrooms and lavatories occupy rooms in the southern part of the west side. Electrical switches, ceiling light fittings, and possibly radiators may date from 1943 when the building was refitted.

From early 1940 until February 1943, Hut 6 housed a section established by Gordon Welchman to decipher German raw Enigma traffic. The section comprised six main departments: the Registration Room for continuous traffic analysis, Intercept Control maintaining contact with intercept stations, the Machine Room, the Sheet Stacking Room (initially using punched cards, superseded in September 1940 by 'cillies' and bombes), the Crib Room preparing cribs for bombes, and the Decoding Room equipped with modified Typex cipher machines. This team played a crucial part in the functioning of Bletchley Park and the decryption of Enigma signals was central to the breaking of the German code and the Allied victory, especially in the Battle of the Atlantic during the first part of the war.

In February 1943 the Hut 6 section moved to Block D. By early March, Hut 6 had been repartitioned for ISK, a section working on Abwehr (German Secret Service) hand ciphers, and renumbered Hut 16. That autumn ISK moved to Block G and the hut was again remodelled 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.

The hut's significance is primarily historic. With Huts 1 and 3 it forms part of a notable group representing the first phase of Bletchley Park's expansion. Externally, while unprepossessing, its wartime appearance is largely unaltered. The survival of its wartime layout and character is relatively good, with the central corridor part of the original building, although whether all present room divisions were present from 1940 is unknown.