Joan Clarke

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Joan Clarke
File:Joan Clarke (cryptanalyst).jpg
Clarke, c. the 1940s
Born Joan Elisabeth Lowther Clarke
(1917-06-24)24 June 1917
West Norwood, London, UK
Died 4 September 1996(1996-09-04) (aged 79)
Headington, Oxfordshire, England, UK
Nationality British
Other names Joan Clarke Murray (1952-1996)
Ethnicity English
Alma mater Newnham College, Cambridge
Occupation Cryptanalyst
Known for Codebreaking at Bletchley Park in WW II
Spouse(s) John Murray (m. 1952–86)
Partner(s) Alan Turing (engaged during 1941 but did not marry)
Awards British Numismatic Society Sanford Saltus Gold Medal (1986)

Joan Elisabeth Lowther Murray, MBE (née Clarke; 24 June 1917 – 4 September 1996) was an English cryptanalyst and numismatist best known for her work as a code-breaker at Bletchley Park during World War II. Though not personally seeking the spotlight, her important role in the Enigma project against Nazi Germany's secret communications earned her awards and citations such as being appointed a Member of the Order of the British Empire (MBE) in 1947.[1]

Early life

Joan Elisabeth Lowther Clarke was born on 24 June 1917 in West Norwood, London, England. She was the youngest child of Dorothy (née Fulford) and the Revd William Kemp Lowther Clarke, a clergyman. She had three brothers and one sister.[2]

Clarke attended Dulwich High School for Girls in south London and won a scholarship to attend Newnham College, Cambridge where she gained a double first degree in mathematics and was a Wrangler.[3][4] She was denied a full degree, however, which Cambridge awarded only to men until 1948.[1]


Codebreaking at Bletchley Park

In June 1940, Clarke was recruited by her former academic supervisor, Gordon Welchman, to the Government Code and Cypher School (GC&CS).[5] She worked at Bletchley Park in the section known as Hut 8 and quickly became one of the practitioners of Banburismus, a cryptanalytic process developed by Alan Turing which reduced the need for bombes. Hugh Alexander, head of Hut 8 from 1943 to 1944, described her as "one of the best Banburists in the section".[6] Alexander himself was regarded as the best of the Banburists. He and I. J. Good considered the process more an intellectual game than a job. It was "not easy enough to be trivial, but not difficult enough to cause a nervous breakdown".[7]

Clarke became deputy head of Hut 8 in 1944.[6][8] She was paid less than the men and believed that she was prevented from progressing further because of her gender.[2]

External video
Murray née Clarke talking about her engagement to Turing

Clarke and fellow code-breaker Alan Turing became very good friends at Bletchley Park. Turing would arrange their shifts so they could be working together, and they also spent a lot of their free time together. In early 1941, Turing proposed marriage to Clarke and subsequently introduced her to his family. After privately admitting his homosexuality to his fiancée, who was reportedly "unfazed" by the revelation, Turing decided that he could not go through with the marriage and broke up with Clarke in mid-1941. Clarke later admitted that she suspected the truth about Turing's homosexuality for some time and it was not much of a surprise when Turing told her about being homosexual.[9][10]

Clarke and Turing had been close friends since soon after they met, and continued to be until Turing's death in 1954. They shared many hobbies and had similar personalities.[1]

After the war

After the war, Clarke worked for GCHQ where she met Lieutenant-Colonel John Kenneth Ronald Murray, a retired army officer who had served in India. They married on 26 July 1952 in Chichester Cathedral. Shortly after their marriage, John Murray retired from GCHQ due to ill health and the couple moved to Crail in Scotland.[4] They returned to work at GCHQ in 1962 where Clarke remained until 1977 when she retired aged 60.[2][11]

Following her husband's death in 1986, Clarke moved to Headington, Oxfordshire, where she continued her research into coinage. During the 1980s, she assisted Sir Harry Hinsley with the appendix to volume 3, part 2 of British Intelligence in the Second World War.[3] She also assisted historians studying war-time code breaking at Bletchley Park. Due to continuing secrecy among cryptanalysts, the full extent of her accomplishments remains unknown.[2]

Numismatic interest

Clarke was a gifted numismatist. She established the sequence of the complex series of gold unicorn and heavy groat coins that were in circulation in Scotland during the reigns of James III and James IV. In 1986, her research was recognised by the British Numismatic Society when she was awarded the Sanford Saltus Gold Medal. Issue #405 of the Numismatic Circular described her paper on the topic as "magisterial."[3][12]

Personal life

Throughout her life, Clarke had a number of hobbies that became passions such as chess, botanical work, and knitting.[1]

On 4 September 1996, Joan Clarke Murray died at her home in Headington.[2]

Portrayal in adaptation

Clarke was portrayed by Keira Knightley in the film The Imitation Game (2014), opposite Benedict Cumberbatch as Alan Turing.[13][14] Turing's surviving niece Inagh Payne described Clarke as "rather plain". Payne thought that Knightley was inappropriately cast as Clarke.[15] Biographer Andrew Hodges criticized the script for having "built up the relationship with Joan much more than it actually was."[14]

However, an article by BBC journalist Joe Miller stated that Clarke's "story has been immortalised." In terms of the film itself, director Morten Tyldum has argued that it shows how Clarke succeeded in her field despite working in a time "when intelligence wasn't really appreciated in women."[1]


  1. 1.0 1.1 1.2 1.3 1.4 "Joan Clarke, woman who cracked Enigma cyphers with Alan Turing". BBC News.<templatestyles src="Module:Citation/CS1/styles.css"></templatestyles>
  2. 2.0 2.1 2.2 2.3 2.4 Lord, Lynsey Ann (2008). "Joan Elisabeth Lowther Clarke Murray". Honours project. University of St Andrews. Retrieved 5 November 2013.<templatestyles src="Module:Citation/CS1/styles.css"></templatestyles>
  3. 3.0 3.1 3.2 Erskine, Ralph. "Murray [Clarke], Joan Elisabeth Lowther (1917–1996)". Oxford Dictionary of National Biography. Oxford University Press. Retrieved 27 October 2013.<templatestyles src="Module:Citation/CS1/styles.css"></templatestyles>
  4. 4.0 4.1 Lord Stewartby (1997). "Obituary Mrs J.E.L. Murray" (PDF). British Numismatic Society. British Numismatic Society. Retrieved 15 November 2014.<templatestyles src="Module:Citation/CS1/styles.css"></templatestyles>
  5. Anderson, L. V. "The Imitation Game: Fact vs Fiction". Retrieved January 3, 2015.<templatestyles src="Module:Citation/CS1/styles.css"></templatestyles>
  6. 6.0 6.1 Burman, Annie. "Gendering decryption – decrypting gender The gender discourse of labour at Bletchley Park 1939–1945" (PDF). Retrieved 27 October 2013.<templatestyles src="Module:Citation/CS1/styles.css"></templatestyles>
  7. Good (1993) p. 157
  8. "Women Codebreakers". Bletchley Park Research. Retrieved 3 November 2013.<templatestyles src="Module:Citation/CS1/styles.css"></templatestyles>
  9. Leavitt, David (2007). The man who knew too much: Alan Turing and the invention of the computer. Phoenix. pp. 176–178. ISBN 978-0-7538-2200-5.<templatestyles src="Module:Citation/CS1/styles.css"></templatestyles>
  10. Grime, James (24 July 2014). "An Alan Turing expert watches the "The Imitation Game" trailer". The Aperiodical. Retrieved 28 July 2014.<templatestyles src="Module:Citation/CS1/styles.css"></templatestyles>
  11. Stewart, Ian (1986). "Obituary: Lieutenant-Colonel J.K.R. Murray" (PDF). British Numismatic Journal. British Numismatic Society. 56: 201–203. Retrieved 5 November 2013.<templatestyles src="Module:Citation/CS1/styles.css"></templatestyles>
  12. "Sanford Saltus Gold Medal". British Numismatic Society. British Numismatic Society. 2013. Retrieved 14 November 2014.<templatestyles src="Module:Citation/CS1/styles.css"></templatestyles>
  13. "Joan Clarke played by Keira Knightley in upcoming film",; accessed 14 November 2014.
  14. 14.0 14.1 "Alan Turing's biographer criticises upcoming biopic for downplaying gay identity".<templatestyles src="Module:Citation/CS1/styles.css"></templatestyles>
  15. Lazarus, Susanna (19 November 2013). "Imitation Game filmmakers accused of romanticising the relationship between Benedict Cumberbatch and Keira Knightley's characters by Alan Turing's niece, Inagh Payne". Radio Times. Retrieved 10 September 2014.<templatestyles src="Module:Citation/CS1/styles.css"></templatestyles>