The Huts and Blocks :
Huts 3, 4, 6 and 8

LINKS to other pages in the Bletchley Park site and to the Colin Day Travelling Days series:

1 : Bletchley Park Estate to 1939
2 : Enigma and GC&CS.
3 : The Poles and Enigma
4 : Turing and the Bombes
5 : The Huts: An overview
6 : German Naval Codes
7 : Huts 3,4,6 and 8
8 : Blocks A,B,C,D,E and F
9 : Views of the Estate (1)
10 : Views of the Estate (2)
11 : Lorenz and Colossus
12 : Finale, Links, Bibliography
Bletchley Park Guest Book:
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ON AVERAGE more than three-thousand coded messages arrived at Bletchley Park each day from the 'Y' Stations - radio receiving units scattered throughout Britain and operated by the RAF and WRAF.

Messages sent by the German forces in morse were intercepted and read by operators working around the clock in eight-hour shifts. They were then relayed by secret land-line or delivered by motor cycle despatch riders to Bletchley to specific 'Huts', depending on whether the messages had come from the German army or air force, navy or another source.

A message intercepted from a U-boat, for instance, would first go to Hut 8 for decoding. After decrypting, it would be passed from Hut 8 to Hut 4 situated near the mansion.

The Italian administrative machine cipher, C 38m, was also broken by Hut 4 during the summer of 1941. This revealed details of the Mediterranean convoys carrying men and materiel to supply the axis forces in North Africa. (Incidentally, Hut 4 now contains the visitors' restaurant and accommodates the Bletchley Park Club.)

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Hut 8 (Right) was responsible for Enigma decrypting. Note the remains of the blast-proofing walls.

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(Right) Hut 4 can be seen in the background. Below the green dome of the mansion the ground floor room was Alastair Denniston's office throughout the war.

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A view of Hut 4, from south of the Mansion. (Left)
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In the early days decrypting work and, later, sorting of messages was carried out in Hut 3. Messages were originally transmitted by teleprinter to the intelligence centre in London from here, but later in the war they were sent to Whaddon Hall for transmission. The asbestos clad structure was one of the few huts to have had its own boiler and central heating system. The roof was, because of the hut's importance, later reinforced with heavy anti-schrapnel sheeting.

Hut 3. (Right)

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Hut 6 became the main centre for decoding the German air force and army messages. It has been said it was from here that the RAF's Air Chief Marshal Dowding was fed information, from which he was able to provide an appropriate response, regarding the German Luftwaffe's intentions during the 1940 Battle of Britain. The late Professor F.H. Hinsley, however, has stated that there is no substance to this claim since it was not until the spring of 1941 that regular decrypts were possible. Prior to that they were confined, from early 1940, to the Norwegian campaign and just two keys used by the Luftwaffe.

The book, "The Hut 6 Story", by Gordon Welchman, one of the 'boffins' at Bletchley during the war, goes into great detail about the work performed here.

Hut 6. (Left)
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A shuttle system for passing decrypts and other messages from one hut to another more speedily and, coincidentally, preventing vital papers (and personnel!) from getting wet, was through a small tunnel constructed to connect Hut 6 and Hut 3. Inside was a tray with a length of string attached to each end. A broom handle rattled inside the tunnel from one hut indicated the need for someone in the opposite hut to pull in the tray into which messages had been placed.

(Right) The gap between Hut 3, situated on the left of the picture, and Hut 6 was the site of the small tunnel described above. A hole was cut in the wall of Hut 6 (just beyond the second window on the right) in a position directly opposite a similar hole in Hut 3.

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