Important People of Cyber – Joan Clarke

We focus on another pioneering woman in the field. In part 3 of our Important People of Cyber series we look at one of the Enigma code breakers; Joan Clarke.

Joan Clarke was born in London in 1917 and from an early age showed an aptitude for numbers. Chess and number games became lifelong passions and she excelled at school. She then went on to win a scholarship to Newnham College, Cambridge.

It was here that Joan demonstrated her talent for mathematics. Even though she achieved excellent scores and a double first grade she was not granted a full degree as at that time women were denied the right. It wouldn’t be until 1948 that she was finally granted one.

Whilst at Cambridge Joan’s skills were noticed and she was recruited into the Government Code and Cypher School (GCCS).


World War Two and Enigma

With World War Two raging and the Nazi’s sweeping across Europe, the Allies needed an advantage if they were to turn the dire situation, they now found themselves in around.

At the time cryptology was not regarded as a job for women. As with most of the other women recruited into the GCCS Joan was initially assigned as an administrative and clerical worker but her mathematical talents were noticed and before long, she was promoted to Hut 8. 

She was then assigned to work with other code breakers including Alan Turing in Hut 8 to crack the Naval Enigma Code which was used to encrypt German naval transmissions. This code was much more complex than the one used by the Luftwaffe and German army.

Despite doing the same work as the men Joan was being paid less than them. To get around this she was promoted to a Linguist despite her not speaking another language. However, the role paid more and was a way of recognising her contribution to the team.

At that point in the war German U-Boat, ‘Wolf Packs’ were causing carnage in the Atlantic, sinking more than 200,000 tonnes of shipping every month from March to July 1941. Britain was close to the brink of running out of supplies and it seemed as though the nation would be starved into surrender. As a result, the cracking of the Enigma code was vital.

At Bletchley Park, Alan Turing invented a new codebreaking technique called Banburism. To speed up their efforts the Banburists developed their own methodologies. Clarke developed her own method to speed up the technique.

Thanks to their efforts, the amount of shipping lost to the German U-Boats declined sharply giving Britain a much-needed reprieve by allowing much-needed supplies to arrive safely from the United States and Canada.

In 1944, Clarke was made Deputy Head of Hut 8, a huge accomplishment in such a male-dominated environment and was a testament to her skills and the high esteem in which her colleagues regarded her

After the War

Following the end of the war, Clarke was awarded an MBE for her codebreaking and was transferred to the newly created GCHQ. It was here that she met her husband Lieutenant-Colonel John Kenneth Ronald Murray. She stayed at GCHQ until her retirement in 1977 at the age of 60.

After leaving GCHQ she assisted several historians who were studying the code breaking of World War Two and Bletchley Park.

Joan passed away in 1996 but will forever be remembered as a pioneer in the development of cryptoanalysis and cryptography. She was a true wartime hero whose contributions saved many lives and helped shorten the duration of the conflict. She is an inspiration to many women working in the field today and continues to inspire women to enter the worlds of mathematics and technology to this day.

For Further Reading

Important People of Cyber – Hedy Lamar

Important People of Cyber – Charles Babbage

A History of Hacking

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