Dorothy Du Boisson

Dorothy Du Boisson

A Colossus Mark 2 computer being operated by Dorothy Du Boisson (left) and Elsie Booker.

Dorothy Du Boisson, MBE, (26 November 1919 – 1 February 2013) was a codebreaker stationed at Bletchley Park during World War II.

Du Boisson joined the Women's Royal Naval Service (known as WRNS) in 1943 and was stationed at the Newmanry in Bletchley Park. Along with other WRNS, she operated codebreaking machines, including the Colossus computer. She was set to work on the first Newmanry Tunny and then on Heath Robinson, before eventually move to Colossus. She was one of four operators who was working with Tunny. To work efficiently, she had to learn how to operate Heath Robinson as well. After Colossus appeared, she operated it under the direction of cryptographer.

When more WRNS were posted to the Newmanry, Du Boisson came off the machines and went into the Ops Rooms as a registrar[1]. She was responsible for logging the tapes in and out and distributing them to the machines. Since there had only two people working in Ops room, Du Boisson had tremendous amount of work to do to record the date and the identity of each tape used on Colossus and Tunny. She knew exactly where each tape was and the machine time spent on it. Moreover, she was responsible for unwinding tapes into buckets and joining them into a loop. This was an essential step for operating Colossus and Heath Robinson since the tape might not stand up to the speed of the machine. After many experiments, Du Boisson found a unique way to realize it by using a special glue, a warm clamp, and French chalk. After the European war was over, Colossi were smashed into fragments on the orders of Churchill.

After the war ended, Du Boisson worked as a typist in the Air Ministry.

To perform the data analyze well, “Du Boisson and other operators in Wrens need to get the data first from a partially electronic machine named Heath Robinson. If it could perform its analysis successfully, the resulting data would be run through the Tunny machine.”

Most of workers aged between 20 and 22, and were put under training sessions in order to get more familiar with the machines, how they operates, what do they do and the maintenance procedures. However, the working shifts could last for long times, up to 70 hours per week. The main reason was that many machines kept running all the time and, since there were few people that actually knew how to operate them, it was necessary to work with three eight-hour shifts every day for weeks. Moreover, due to this stressful working load, many errors in the operations started to appear. Due to limitations in the machines, when a mistake was found, in many cases it was necessary to redo the work all over again.