The Bletchley Girls
In Great Britain, cryptanalysts were based at a 19th-century mansion in Milton Keynes, Buckinghamshire. The British Government Code and Cypher School included such great code-breakers and mathematicians as Alan Turing, Gordon Welchman, Hugh Alexander, and Stuart Milner-Barry. Approximately 10,000 people were working there by the end of the war, and it has been estimated that of that number, around two-thirds were women. The majority of these were employed in clerical tasks or work that was considered monotonous. However, some were hired as mathematicians and cryptanalysts and proved themselves to be equal to men in their skill, intelligence, and ingenuity. This article looks at just three of those remarkable women, although, of course, many other names who could have appeared here (although it would probably have turned into a book rather than an article).
Joan Clarke was born on June 24, 1917, in London. She entered Newnham College, Cambridge, to study mathematics and proved to be an exceptional student. In 1939, Joan graduated from Newnham College with a double First in Mathematics. However, due to Cambridge’s policy at the time, women were not allowed into the academic community, so the qualification was really nothing more than a piece of paper.[i]
In 1940, because of her outstanding skill in mathematics, she was offered a post at the Government Code and Cypher School (GCCS) at Bletchley Park in Buckinghamshire. The main reason for the creation of the GCCS was to break the various Enigma machines used by Germany, Italy, and Japan. This coding machine was made up of, among other components, several rotors lined up along a spindle and an electrical circuit. Its complexity was thought to make its encryption unbreakable. This belief was echoed by Alastair Denniston, the first head of Bletchley Park, who believed that the attempts to break Enigma would be futile. However, his pessimism only served to spur on the code breakers under him to prove him wrong.[ii]
On arriving at Bletchley, Joan was assigned to Hut 8, which, at the time, was led by Alan Turing, initially to work with a group of women, called ‘the girls,’ who handled mainly clerical tasks. She was soon promoted to Linguist Grade, despite not being able to speak another language, and joined Alan Turing’s team of cryptanalysts. This team, which included Tony Kendrick and Peter Twinn, had been given the task of breaking the German Naval Enigma, known as ‘Dolphin.’ Although the Army and Luftwaffe Enigmas were difficult enough, Dolphin was far more complex than either as it contained two extra rotors.[iii] By the beginning of spring, 1940, the need to break the code grew ever more urgent, as Allied Naval convoys became targets for German U-boats. At one point, the attacks were so severe, that Britain was only three days away from running out of food.
The break they needed came in May 1940, when a German patrol boat, carrying matched plaintext and Enigma code, was captured off the Norwegian Coast. One of the tasks given to Joan was to attempt to find a key in the new material using an electro-mechanical machine called ‘The Bombe.’ After Alan Turing’s invention of a code-breaking technique known as Banburismus, and the capture of German trawlers with further cipher equipment and codes, the team achieved their finest breakthrough. Joan, already acknowledged as one of the finest and keenest Banburists (and the only female one), continued to work with the method to break Enigma communications until ultra-fast Bombes became available in 1943.[iv] It was through the efforts of Joan and the rest of Turing’s team that fewer convoy ships were sunk by the German U-boat Wolf Packs, and many lives were saved.
With the Dolphin Enigma broken, the Naval Enigma team became tasked with breaking another Enigma, code-named ‘Shark.’ However, this was soon taken over by US code-breakers instead. In 1944, Joan was made Deputy Head of Hut 8 and continued to work on the Naval Enigma machine until the war ended.
Because of her contributions to code-breaking, Joan was made a Member of the British Empire (MBE) in 1947.[v] In 1952, she married Colonel J.K. Murray and moved to Scotland. There, she adopted her husband’s love of Scottish history and numismatics. However, ten years later, they moved back to England, and Joan took up a post with the Government Communications Headquarters (GCHQ), where she worked until retiring in 1977 at the age of 60.[vi] After her husband’s death in 1986, Joan moved to Oxford where she continued her research into numismatics. A year later she was awarded the Sandford Saltus medal for her contributions to the subject.[vii] Joan Clarke died in 1996.
Despite her successes at Bletchley, much of her work is still shrouded in secrecy. Her story has also been put into the shade by that of Alan Turing’s tragic life, especially as she was briefly engaged to him in 1941. Her role was played by Keira Knightly in the ‘Imitation Game’ – a film about Alan Turing’s life and work at Bletchley Park.
Mavis Batey neé Lever
Mavis Batey was born Mavis Lilian Lever in 1921 in Dulwich, London. She began studying German at University College London, but when World War Two was declared, she decided to volunteer to help in the war effort. In her own words:
‘I was concentrating on German Romantics and then I realised the German Romantics wold son be overhead and I thought well, I really ought to do something better for the war effort. I said I’d train as a nurse and their response was: ‘Oh no you don’t. You use your German.’ So I thought, great. This is going to be an interesting job, Mata Hari, seducing Prussian officers. But I don’t think either my legs or my German were good enough because they sent me to GCCS.’[viii]
Her first job was with a London section, looking for coded spy messages in the personal columns of The Times, but she was soon moved to Bletchley Park and placed in Hut 6, which was under the leadership of veteran code-breaker Dillwyn (Dilly) Knox. Her skill was such that she was even able to identify individual enemy operators by the style of their messages.[ix] Mavis was soon working on the Italian Naval Enigma code alongside Knox in ‘The Cottage.’ She managed to break the code by late March 1941, which led to the thwarting of an attack on a Royal Navy convoy by the Italian Navy a few days later.[x] Other successes included deciphering a message between Belgrade and Berlin that led to the breaking of the supposedly undecipherable Abwehr Enigmas machine.
After the war, Mrs. Mavis Batey (she had married fellow code-breaker Keith Batey in 1942) worked for the Diplomatic Service. She became interested in garden history and wrote several books on the subject. In 1971, she became the President of the Garden History Society, and later won the Veitch Memorial Medal and the MBE for her services to garden conservation.[xi] During this time, she also wrote about her time at Bletchley Park, including a biography of Dilly Knox. Mavis died in 2013, three years after the death of her husband.
Born in 1903 in London, Margaret excelled in French, music, and mathematics while at school. Her father was killed when his ship was sunk by a German U-boat in World War One, but before that happened, he wrote to her regularly. His words were of encouragement for Margaret to keep up her studies and be successful in life and must have been a large motivation for her when she took up her later work.[xii]
After gaining a Bachelor of Arts Degree at Bedford College, University of London in 1921, Margaret worked as a statistician for the National Association of Manufacturers. She remained in the same employment until the outbreak of World War Two when she was offered a job at Bletchley Park. She soon found herself posted to the Cottage, in Dilly Knox’s team, where she often worked side-by-side on projects with Mavis Lever (later Batey).[xiii] Interestingly, at a time when women were rarely regarded as intellectually strong enough to work in such male-dominated professions, Dilly believed that they actually possessed better cryptographic skills than men due to their patience and diligence, and considered Margaret to be the 4th or 5th best cryptographer at Bletchley.[xiv] Margaret specialized in the breaking of German and Russian ciphers and was one of the team that broke the seeming unbreakable Abwehr Enigma code. Her achievements didn’t go unnoticed, and she was awarded a promotion and a pay rise for her valuable contributions.
After the war, Margaret worked for GCHQ until her retirement in 1963. She never spoke of her work at Bletchley even when, later on, others were doing so. She died at Worcester in 1983.
As I stated at the beginning of this article, many women worked at both Bletchley and at Arlington Hall Station in the US. With the relaxing of secrecy laws around their work, many books have now been written about their fantastic achievements that ended up saving lives and shortening the war. There are too many to list here, but a quick search on Google or Amazon should point you in the right direction. In particular, I recommend Liza Munday’s Code Girls, and Michael Smith’s The Debs of Bletchley Park.
Women were not the only ones to have their code-breaking histories erased. There was also a concealed unit of African-Americans working on commercial codes at Arlington Hall Station in America. Today it is more than challenging to find anything on them, but the next two articles will try and bring to light the extraordinary work they did for their country in a time when blacks and whites were still segregated.
[i] ‘Joan Elizabeth Lowther Clarke Murray,’ Maths History, St. Andrews, accessed at http://mathshistory.st-andrews.ac.uk/Biographies/Clarke_Joan.html
[ii] Joel Greenberg, Alastair Denniston: Code-Breaking From Room 40 to Berkeley Street and the Birth of GCHQ, Grub Street Publishers, Jul 2017, accessed from Google Books Online at https://bit.ly/3dvcScB
[iii] ‘Joan Elizabeth Lowther Clarke Murray,’ Maths History, St. Andrews, accessed at http://mathshistory.st-andrews.ac.uk/Biographies/Clarke_Joan.html
[v] Joe Miller, ‘Joan Clarke, Woman Who Cracked Enigma Cyphers with Alan Turing,’ BBC, 11/10/2014, accessed at https://www.bbc.co.uk/news/technology-29840653
[vi] ‘Joan Clarke,’ GCHQ, 07/15/2019, accessed at https://www.gchq.gov.uk/information/joan-clarke
[vii] ‘Joan Clarke,’ History of Scientific Women, accessed at https://scientificwomen.net/women/clarke-joan-158
[viii] Michael Smith, The Secrets of Station X: How the Bletchley Park Codebreakers Helped Win the War, Biteback Publishing, October 2011, Chapter 6, accessed at https://bit.ly/33P0Y8V
[ix] Tom Chivers, ‘Could You Have Been a Codebreaker at Bletchley Park?’ The Telegraph, 10/12/2014, accessed at https://www.telegraph.co.uk/history/world-war-two/11151478/Could-you-have-been-a-codebreaker-at-Bletchley-Park.html
[x] Josephine Liptrott, ‘Biography: Mavis Batey – Code-Breaker,’ The Heroine Collective, 09/02/2016, accessed at http://www.theheroinecollective.com/mavis-batey/
[xi] Michael Smith, ‘Mavis Batey Obituary,’ The Guardian, 11/20/1013, accessed at https://www.theguardian.com/world/2013/nov/20/mavis-batey
[xii] Kerry Johnson, Dear Code Breaker: The Letters of Margaret Rock, BookTower Publishing, 2 edition, 09/02/2013, p.13
[xiii] ‘Margaret Rock,’ Spartacus Educational, accessed at https://spartacus-educational.com/Margaret_Rock.htm
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