Woman of the Day Bletchley Park codebreaker Joan Clarke born OTD 1917 London, deputy head of Hut 8 (on less pay than men of course), the only woman skilled at Banburismus, the cryptanalytic process developed by Alan Turing. She and her team reduced Allied shipping losses by 80%.
Joan studied maths at Cambridge and in 1940, attained a double first and was denied a degree. Standard for women then; until 1948, Cambridge only awarded them to men. However, her supervisor realised her potential and persuaded her to come to the Government Code and Cypher School at Bletchley Park. She wasnโt told what the job would entail, only that โThe work didn't really need mathematics but mathematicians tended to be good at it .โ
Joan arrived at Bletchley Park on 17 June 1940 and as with all girls at Bletchley (yes, it really did refer to grown women as girls), she was assigned to clerical work. Within days, it was plain that it was a criminal waste of her talents. They found an extra table for her and squeezed it into the small room in Hut 8 used by Alan Turing and his team.
It required promotion though. Civil Service protocol, you understand. There was no such thing as a female cryptanalyst so they regraded her as a linguist on two quid a week, less than the men. โI enjoyed answering a questionnaire with 'Grade: Linguist, Languages: none!โ
During WW2, every branch of Germanyโs military intelligence and civil services communicated via Enigma, an electro-mechanical device with rotating wheels and rotors that scrambled plain text messages into jumbled cypher text. Each service used a separate Enigma setting but they all changed on a daily basis. Unless you could work out the daily key, the odds of deciphering a cipher were one in 150 million million million.
The Germans were confident Enigma was unbreakable. The first Head of Bletchley Park thought so too: โAll German codes are unbreakable.โ
Before the Bombe machine was invented and refined in August 1940, Alan Turing had devised Banburismus, a way to solve a puzzle by finding clues in repeated patterns, which helped codebreakers to work out the Enigma's daily settings faster and decide secret German messages but it was laborious work.
There were eight male Banburists and Joan. She became one of the best. Her work was crucial to Britainโs survival because the task for her and her team was to crack the German navyโs ciphers, acknowledged to be the hardest of all. U-boats were deadly, hunting and sinking Allied shipping in the Atlantic - at one stage, Britain was just three days from running out of food - and the toll on Allied lives was horrific.
Soon after Joan arrived at Bletchley, she and her colleagues broke approximately six days of encrypted traffic over a period of three months but she was dedicated, stayed late at her table, never gave up. Before long, it showed. From March and June 1941, U-boats were sinking 282,000 tons of shipping a month. By November 1941, it had reduced significantly to 62,000 tons per month as her intell was relayed to Allied ships which torpedoed or circumnavigated U-boats, saving thousands of lives.
Off-duty, Joan and Alan Turing were close friends with shared interests. โWe did do some things together, perhaps went to the cinema and so on, but certainly, it was a surprise to me when he saidโฆ.โWould you consider marrying me?โโ She said yes but knew he โhad this homosexual tendency. Naturally, that worried me a bit, because I did know that was something which was almost certainly permanent, but we carried on."
A few months later, he broke off the engagement but they remained close friends. They enjoyed each otherโs company and respected each otherโs analytical minds. When he wrote a reference book about the Enigma Theory for new recruits to Hut 6 and Hut 8, he entrusted Joan to proofread it and give him feedback about its readability.
Post-war, Joan married another Bletchley Park codebreaker and rejoined GCHQ from 1962 until 1977 when she officially retired but there is reason to believe that she helped to track down an Argentinian submarine sunk in 1982 during the Falklands War.
Joan died in 1996, aged 79, and the strict secrecy over the wartime work of Bletchley means we may never know how much of a debt we owe her but it is estimated that the intelligence produced at Bletchley Park shortened the war by two to four years, and saved millions of lives.
Winston Churchill described its codebreakers as โthe geese who laid the golden eggs and never cackledโ.
