Bletchley Park

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Bletchley Park
Bletchley Park - Draco2008.jpg
The Mansion
Grid reference: SP863339
Location: 51°59’47"N, 0°44’34"W
Town: Bletchley
Owned by: Bletchley Park Trust

Bletchley Park is a grand country mansion at Bletchley in northern Buckinghamshire, now surrounded by the new town development of Milton Keynes. It is world famous as the central site of the Government Code and Cypher School during the Second World War which regularly penetrated the secret communications of the Axis Powers, and most importantly the German Enigma and Lorenz ciphers.

Today the house is preserved as a museum and educational centre, primarily to the work of the codebreakers of Bletchley.

The official historian of Second World War British Intelligence has written that the "Ultra" intelligence produced at Bletchley shortened the war by two to four years, and that without it the outcome of the war would have been uncertain.[1]


The stableyard cottages

Bletchley appears in the Domesday Book as part of the Manor of Eaton. Browne Willis built a mansion there in 1711, but after Thomas Harrison purchased the property in 1793 this was pulled down. The estate was first known as Bletchley Park after its purchase by Samuel Lipscomb Seckham in 1877.[2] The estate of 581 acres was bought in 1883 by Sir Herbert Samuel Leon, who expanded the then-existing farmhouse[3] into the present "maudlin and monstrous pile" combining Victorian Gothic, Tudor Revival and Dutch Baroque styles.

In 1938, the mansion and much of the site was bought by a builder planning a housing estate, but in May 1938 Admiral Sir Hugh Sinclair, head of the Secret Intelligence Service (SIS or MI6) bought the mansion and 58 acres for use by GC&CS and SIS in the event of war.[4]

A key advantage seen by Sinclair and his colleagues (inspecting the site under the cover of "Captain Ridley's shooting party")[5] was Bletchley's geographical centrality. It was almost immediately adjacent to Bletchley railway station, where the "Varsity Line" between Oxford and Cambridge, whose universities were expected to supply many of the code-breakers, met the main West Coast railway line connecting London, Birmingham, Manchester, Liverpool, Glasgow and Edinburgh.

Watling Street, the main road linking London to the north-west (now the A5) was close by, and high-volume communication links were available at the telegraph and telephone repeater station in nearby Fenny Stratford.

Bletchley Park was known as "B.P." to those who worked there.[6] "Station X" (X=Roman numeral ten), "London Signals Intelligence Centre", and "Government Communications Headquarters" were all cover names used during the war.[7] The formal posting of the many Wrens working there (of the Women's Royal Naval Reserve) was to 'HMS Pembroke V'.

Listening stations

Initially, a wireless room was established at Bletchley Park. It was set up in the mansion's water tower under the code name "Station X",[8] a term now sometimes applied to the codebreaking efforts at Bletchley as a whole.

Due to the long radio aerials stretching from the wireless room, the radio station was moved from Bletchley Park to nearby Whaddon Hall to avoid drawing attention to the site.[9][10]

Subsequently, other listening stations, such as the ones at Chicksands in Bedfordshire, Beaumanor Hall, Leicestershire (where the headquarters of the War Office "Y" Group was located) and Beeston Hill Y Station in Norfolk, gathered raw signals for processing at Bletchley. Coded messages were taken down by hand and sent to Bletchley on paper by motorcycle despatch riders or (later) by teleprinter.

Bletchley Park is mainly remembered for breaking the German Enigma cypher, but its greatest cryptographic achievement may have been the breaking of the German on-line teleprinter Lorenz cipher (known at GC&CS as Tunny).

Additional buildings

The wartime needs required the building of additional accommodation.[11]


Hut 1
Hut 4, now a bar and restaurant for the museum
Hut 6

Often a hut's number became so strongly associated with the work performed inside that even when the work was moved to another building it was still referred to by the original "Hut" designation.[12][13] are:

  • Hut 1: The first hut, built in 1939[14] used to house the Wireless Station for a short time,[8] later administrative functions such as transport, typing, and Bombe maintenance. The first Bombe, "Victory", was initially housed here.[15]
  • Hut 2: A recreational hut for "beer, tea, and relaxation".[16]
  • Hut 3: Intelligence: translation and analysis of Army and Air Force decrypts[17]
  • Hut 4: Naval intelligence: analysis of Naval Enigma and Hagelin decrypts[18]
  • Hut 5: Military intelligence including Italian, Spanish, and Portuguese ciphers and German police codes.[19]
  • Hut 6: Cryptanalysis of Army and Air Force Enigma[20]
  • Hut 7: Cryptanalysis of Japanese naval codes and intelligence.[21][22]
  • Hut 8: Cryptanalysis of Naval Enigma.
  • Hut 9: ISOS (Intelligence Section Oliver Strachey).
  • Hut 10: Secret Intelligence Service (SIS or MI6) codes, Air and Meteorological sections.[23]
  • Hut 11: Bombe building.[24]
  • Hut 14: Communications centre.[25]
  • Hut 15: SIXTA (Signals Intelligence and Traffic Analysis).
  • Hut 16: ISK (Intelligence Service Knox) Abwehr ciphers.
  • Hut 18: ISOS (Intelligence Section Oliver Strachey).
  • Hut 19: Currently used by 2366 ATC Squadron
  • Hut 23: Primarily used to house the engineering department. After February 1943, Hut 3 was renamed Hut 23 (the reason it was not named Hut 13 in a similar way to the other huts, was due to the belief that the number 13 was unlucky).


In addition to the wooden huts there were a number of brick-built "blocks".

  • Block A: Naval Intelligence.
  • Block B: Italian Air and Naval, and Japanese code breaking.
  • Block C: Stored the substantial punch-card index.
  • Block D: Enigma work, extending that in huts 3, 6, and 8.
  • Block E: Incoming and outgoing Radio Transmission and TypeX.
  • Block F: Included the Newmanry and Testery, and Japanese Military Air Section. It has since been demolished.
  • Block G: Traffic analysis and deception operations.
  • Block H: Tunny and Colossus (now The National Museum of Computing).

After the War


Much of Bletchley's equipment and documents was destroyed at the end of the war, and the secrecy imposed on Bletchley staff remained in force, so that most relatives never knew more than that a child, spouse, or parent had done some kind of secret war work,[26] or were told a cover story about clerical or statistical work. Churchill referred to the Bletchley staff as "the geese that laid the golden eggs and never cackled".[27] That said, occasional mentions of the work performed at Bletchley Park slipped the censor's net and appeared in print.[28]

Public discussion of the work at Bletchleyy Park began only with the publication of F W Winterbotham's The Ultra Secret in 1974.[29] In 2009 the British government announced that Bletchley personnel would be recognised with a commemorative badge.[30]


After the war, the site passed through a succession of hands[31] and saw a number of uses, including as a teacher-training college and local GPO headquarters. By 1991, the site was nearly empty and the buildings were at risk of demolition for redevelopment.

In February 1992, the Milton Keynes Borough Council declared most of the Park a conservation area, and the Bletchley Park Trust was formed to maintain the site as a museum. The site opened to visitors in 1993, and was formally inaugurated by HRH The Duke of Kent as Chief Patron in July 1994. In 1999, the Trust concluded an agreement with the landowner, giving control over much of the site to the Trust.[32]


View of the back of the rebuilt Bombe

Block B houses the main collection relating to the wartime codebreaking efforts, including the rebuilt 'Bombe' machine[33] and the Enigma machine collection, extensive displays relating to wartime codebreaking and espionage generally.

As well as The National Museum of Computing, the park is also home to a number of other exhibits.[34]

  • The Mansion
  • Bletchley Park Garage
  • Home Front Display exhibits include rationing, evacuation, the Blitz, war-time wash day, and "Make Do & Mend".
  • The American Garden Trail
  • 65th Nachrichten Abteilung, a German Second World War Signals Group, depicting a receiving and transmitting station with many items of original equipment, including an Enigma machine.
  • Pigeons at War
  • Children's Corner

Other institutions

The rebuilt Colossus computer in Block H

Bletchley Park today also houses:

  • The National Museum of Computing (in Block H)
  • The RSGB National Radio Centre (The Radio Society of Great Britain)

In popular culture

Bletchley Park has appeared in numerous television and film guises and other works, including:

  • The Secret War (1977 BBC television series)
  • Danger UXB (1979)
  • The Imitation Game (play) concluding at Bletchley Park
  • Breaking the Code (1986 play)
  • Cryptonomicon a novel by Neal Stephenson, 1999, has a fictionalised version of Bletchley Park
  • Enigma', 1995 novel and 2001 film (the latter filmed at nearby Chicheley Hall)
  • Bletchley Park plays a significant role in the Connie Willis 2010 novel All Clear.
  • The Bletchley Circle (ITV, 2012) a set of 1950s murder mysteries involving four female former Bletchley code breakers
  • The Imitation Game (2014 film)

Outside links

("Wikimedia Commons" has material
about Bletchley Park)


  1. Hinsley 1996
  2. Morrison, p. 89
  3. Edward, Legg (1999), "Early History of Bletchley Park 1235-1937", Bletchley Park Trust Historic Guides (1) 
  4. Morrison, pp. 102–103
  5. McKay 2010, p. 11
  6. Briggs 2011, p. 1
  7. Aldrich 2010, p. 69
  8. 8.0 8.1 Watson 1993, p. 307
  9. Smith & Butters 2007, p. 10
  10. Pidgeon 2003
  11. Watson, Bob, Appendix: How the Bletchley Park buildings took shape, pp. 306–310  in Hinsley & Stripp 1993, pp. 149–166
  12. Some of this information has been derived from The Bletchley Park Trust's Roll of Honour.
  13. Smith & Butters 2007
  14. Tony Sale "Bletchley Park Tour", Tour 3
  15. Tony Sale, Virtual Wartime Bletchley Park: Alan Turing, the Enigma and the Bombe,, retrieved 7 July 2011 
  16. McKay 2010 p52
  17. Millward 1993, p. 17
  18. Dakin 1993, p. 50
  19. Seventy Years Ago This Month at Bletchley Park: July 1941,, retrieved 8 July 2011 
  20. Welchman 1997
  21. Loewe 1993, p. 260
  22. Scott 1997
  23. Kahn 1991, pp. 189–90
  24. Tony Sale "Bletchley Park Tour", Tour 4
  25. Beaumanor & Garats Hay Amateur Radio Society "The operational huts"
  26. Hill 2004, pp. 129–35
  27. Lewin 2001, p. 64
  28. Thirsk 2008, pp. 61–68
  29. F.W. Winterbotham (1974), The Ultra Secret, London: Weidenfeld & Nicolson 
  30. "Enigma codebreakers to be honoured finally", The Daily Telegraph, 
  31. BellaOnline "Britain's Best Kept Secret"
  32. Bletchley Park Trust "Bletchley Park History"
  33. John Harper "The British Bombe"
  34. What to see at Bletchley Park, Bletchley Park Trust,, retrieved 26 May 2015