Hut 6

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Hut 6 at Bletchley Park in 2004

Hut 6 was a wartime section of the Government Code and Cypher School (GC&CS) at Bletchley Park, Buckinghamshire, Britain, tasked with the solution of German Army and Air Force Enigma machine cyphers. Hut 8, by contrast, attacked Naval Enigma. Hut 6 was established at the initiative of Gordon Welchman, and was run initially by Welchman and fellow Cambridge mathematician John Jeffreys.

Welchman's deputy, Stuart Milner-Barry, succeeded Welchman as head of Hut 6 in September 1943, at which point over 450 people were working in the section.[1]

Hut 6 was partnered with Hut 3, which handled the translation and intelligence analysis of the raw decrypts provided by Hut 6.


Hut 6 was originally named after the building in which the section was located. Welchman says the hut was 20 yards (18m) long by 10 yards (9m) wide, with two large rooms at the far end – and no toilets. Staff had to go to another building. Irene Young recalled that she "worked in Room 82, though in typical Bletchley fashion there were not eighty-one rooms preceding it". She was glad to move from the Decoding Room "where all the operators were constantly having nervous breakdowns on account of the pace of work and the appalling noise" to the Registration Room which arranged intercepts according to callsign and frequency. [2]

As the number of personnel increased, the section moved to additional buildings around Bletchley Park, but its name was retained, with each new location also being known as 'Hut 6'. The original building was then renamed 'Hut 16'.


John Jeffreys was initially in charge of the Hut with Gordon Welchman until May 1940; Jeffreys was diagnosed ill in 1940, and died in 1944. Welchman became official head of section until autumn 1943, subsequently rising to Assistant Director of Mechanisation at Bletchley Park. Hugh Alexander, was a member February 1940 – March 1941 before moving to become head of Hut 8. Stuart Milner-Barry joined early 1940 and was in charge from autumn 1943 to the end of the war.

One codebreaker concerned with Cryptanalysis of the Enigma, John Herivel, discovered what was soon dubbed the Herivel tip or Herivelismus. For a brief but critical few months from May 1940, the "tip", in conjunction with operating shortcomings or "cillies", were the main techniques used to solve Enigma. The "tip" was an insight into the habits of the German machine operators allowing Hut 6 to easily deduce part of the daily key. David Rees is credited with the first decode using the Herivel Tip.[3]

In 1942, Welchman recruited fellow Marlborough Collegers, Bob Roseveare and Nigel Forward. Roseveare started in the Watch working on Luftwaffe messages before moving to the Quatch, a small backroom group that decoded non-current messages.

In Hut 6 were the Machine Room, plus the Decoding Room and Registration Room with mainly female staff under Harold Fletcher, a school and university friend of Gordon Welchman.[4][5] In 2014 one of these female staff, Mair Russell-Jones, published a posthumous memoir of her work there.[6]

Other notable individuals include:

See also[edit]


  1. ^ Ralph Erskine, Barry, Sir (Philip) Stuart Milner- (1906–1995), Oxford Dictionary of National Biography, 2004.
  2. ^ Young (1990) p 74
  3. ^ John Herivel (2008). Herivelismus and the German military Enigma. Kidderminster: M. & M. Baldwin.
  4. ^ Briggs (2011), p 84-85
  5. ^ Welchman (1982) p 103-4
  6. ^ Robin Turner, "Bletchley Park uncovered: The secret life of the Welsh World War II codebreaker", Wales Online, July 27, 2014.
  7. ^ J. M. Whittaker, ‘Aitken, Alexander Craig (1895–1967)’, rev. Anita McConnell, Oxford Dictionary of National Biography, Oxford University Press, 2004; online edn, May 2006.
  8. ^ "Bletchley Park | Roll of Honour — undefined". Bletchley Park. Bletchley Park Trust. Retrieved 10 October 2017.
  9. ^ Welchman (1982) p 86-7
  10. ^ Welchman (1982) p 84
  11. ^ Head of Registration Room
  12. ^ Welchman 1982, pp. 121, 122.
  13. ^ Briggs (2011) p 8, 45
  14. ^ Welchman 1982, pp. 113, 131, 167, 168.
  15. ^ Bletchley Park Summary of Service, 2013


Coordinates: 51°59′51″N 0°44′32″W / 51.99746°N 0.74209°W / 51.99746; -0.74209