Women Code Breakers: Forgotten by History

These three tech pioneers helped solve Enigmas at Bletchley Park

5 February 2015
After watching The Imitation Game, the movie about the life of British mathematician Alan Turing, I came away wondering what exactly was Joan Clarke’s job (the part played by Keira Knightley) as well the jobs of all those other women in the film shown toiling away. The Oscar-nominated film showed Clarke assisting the team that conducted code-breaking work at Bletchley Park during World War II but it failed to explain that she was also a cryptanalyst. Nor did it describe what those several dozen other women were doing in what was called Hut 6. Were they administrative clerks? Typists? Telephone operators? To my surprise, they were also code breakers.

The contributions by these women have rarely been showcased since the work at Bletchley became declassified, with some recent exceptions. The 2013 e-book, Dear Codebreaker by author and historian Kerry Howard, shed some light on one, Margaret Rock. The Bletchley Circle TV series was launched in 2012 and is about four fictional code breakers who reunited in 1952 to track down a serial killer.

With Knightly’s nomination by the Academy of Motion Picture Arts and Sciences for best actress in a supporting role, I’d like to recognize the achievements of the real-life Clarke as well as two others who helped shorten World War II and save thousands of lives.

  • JOAN CLARKE

    Clarke was recruited in 1939 into the Government Code and Cypher School (GC&CS) by one of her supervisors at Cambridge, where she earned what was called a double first in mathematics, according to the BBC. She did not receive a full degree because women were denied them until 1948. As was typical for the “girls” at Bletchley (they were always referred to as girls, not women), Clarke was supposed to work on translating army and air force Enigma messages in Hut 6 where the women worked. But within days her abilities were recognized, and an extra table was installed for her in Hut 8, the nerve center occupied by Turing and the others where the quest to crack German Enigma ciphers took place.

    According to “An Historian Goes to the Movies”, Clarke’s history in the movie is misrepresented. In the film, she is recruited because she solved a crossword puzzle in a newspaper; the puzzle was a tool to find people with unidentified cryptanalysis skills. Although Turing did recruit some people that way, Clarke was not one of them. In reality, she had known Turing at Cambridge, and after she was hired at Bletchley as part of the stenographic pool, she was promoted on the basis of her outstanding mathematical skills.

    In order to promote her to a higher salary grade, Clarke had to be classified as a linguist because England’s Civil Service had no such position as a senior female cryptanalyst. She would later take great pleasure in filling in forms with the line: “Grade: linguist, Languages: none.”

    Clarke was the only woman who worked in Hut 8 and was eventually promoted to be its deputy head, becoming its longest-serving member. She was appointed Member of the Order of the British Empire (MBE) in 1947, which is given “for a significant achievement or outstanding service to the community.”

    She died in 1996 at the age of 79.

  • MARGARET ROCK

    With her degrees in mathematics and French from the University of London’s Bedford College, as well as her post-graduation work in statistics, it’s no surprise that Rock was recruited to join Dillwyn (Dilly) Knox, one of the Enigma Machine code breakers and head of Intelligence Service at the GC&CS. According to Smithsonian magazine, Rock started in April 1940 and had impressed Knox so much by the end of August 1940 that he wrote to the personnel department:Miss Rock is entirely in the wrong grade. She is actually 4th or 5th best of the whole Enigma staff and quite as useful as some of the ‘professors.’ I recommend that she should be put on the highest possible salary for anyone of her seniority.Rock, like Clarke, received a promotion to the grade of linguist. She worked on cracking the German and Russian codes. Rock was also appointed MBE, in 1945.

    Kerry Howard’s book features letters between Rock and her brother John, a British parachutist and a pioneer of its Glider Pilot Regimen, which was established in 1942 as a unit of the British airborne forces during World War II. They discussed the fall of France, the sustained bombing of the United Kingdom by Germany known as the Blitz, John’s missions, as well as the secret work at Bletchley Park. She was 80 when she died in 1983.

  • MAVIS LEVER BATEY

    Batey, whose maiden name was Lever, was a single 19 year old when she arrived at Bletchley Park in May 1940. She was midway through her course in German linguistics at University College London when she was recruited. Normally, new employees to GC&CS took a six-month course at the Inter-Services Special Intelligence School before trying to solve machine ciphers but, according to The Telegraph, Dilly Knox greeted her with the words: “Hallo, we’re breaking machines. Have you got a pencil? Here, have a go.”

    Batey helped solve the GGG Enigma machine, made crucial contributions to the solutions of Enigmas, and broke many vital signals. She decrypted a message that led to a British victory over the Italian navy in the Mediterranean. She also was the first to crack the secret messages of the Abwehr, a breakthrough that helped ensure the success of the D-day landings. The Abwehr was a German military intelligence (information gathering) organization that existed from 1920 to 1945. Batey, together with Rock, are credited with helping to solve 10 different Enigmas: 7 Abwehr and Sicherheitsdienst Enigmas, 2 Italian naval Enigmas, and the Spanish military attaché Enigma.

    She met her husband and fellow code breaker, Keith Batey, at Bletchley. The couple had each written independently for the classified World War II report on the breaking of German secret service codes called the History of Adwehr Code Breaking, and never gave the secret away to each other despite being married. When they married in 1942, they were put in different sections of Bletchley Park and forbidden from talking about their work. When Batey was presented with a copy of the report in 2011, it was the first time she had seen what her husband had been working on during their time there. Ironically, she was appointed MBE in 1987 not for her code breaking work, but for services to the preservation and conservation of historic gardens. She died in 2012 at the age of 92.


The Imitation Game has been nominated for a total of eight Academy Awards including best picture, best director, and best actor. The ceremony will be broadcast on 22 February. Good luck to all, especially Knightly. I’m sure these pioneering women would be rooting for you.

Do you know of other unsung women heroes in engineering and technology? What contributions have they made that haven’t been recognized?

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