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First female business computer programmer dies

Mary Coombs, the first woman to write programs for Lyons Electronic Office, has died at the age of 93

Mary Clare Coombs, née Blood, born 4 February 1929, has died following complications arising after a Covid-19 infection.

Coombs originally joined Lyons & Co in 1952 as a management trainee, following a holiday job arranged for her by her father, the company’s senior medical doctor. Initially, she was put to work in the company’s statistical office operating a calculating machine, but was soon offered the chance to join the Lyons Electronic Office (LEO) team, writing programs for the world’s first business computer.

Recalling her experience of working on the LEO, Coombs said: “We were all engaged in a big adventure.” She joined the computing team when there were just three programmers on board – all men – becoming the only woman in a class of 12 on an introductory computer appreciation course. From there, it was straight into payroll applications for a rapidly growing range of external clients, as well as developing programs for internal company use.

It was a huge challenge. Not only had much of the work never been done before, she said it also involved working on a notoriously unreliable valve computer that had just 2 KB of computer storage compared with the many gigabytes available to today’s programmers.

“When it was LEO 1, you had to know a lot about the machine itself because there was so little storage space that every instruction had to be essential, or it had to be knocked out,” she said.

Along with programming the LEO, she also worked as a programmer, handling payroll at companies such as Ford Motor Company, and was involved in a variety of jobs including tax tables for the Inland Revenue, Met Office work and the calculation of ballistics for the Army. She went on to become a supervisor and worked to locate and repair coding errors in the programs created by others.

Family commitments meant that she ceased full-time programming in 1964, but continued to work part-time editing computer manuals, and for a few months ran a computer programming course for severely disabled residents at the Princess Marina Centre, Seer Green, sponsored jointly by ICL and Buckinghamshire County Council.

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It was not until late 1969 that she ended her formal connection with the LEO team. 

Coombs returned to full-time employment in September 1973 as a primary school teacher, completing a three-year postgraduate teaching course in 1976. She retired from teaching in 1985 and went on to work as a buyer in the water treatment industry.

In 1955, she married John Coombs, himself briefly a computer programmer on the LEO team, who died in 2012. Together they had a daughter, Anne, who died aged six. Between 1965 and 1969, they adopted three children, Andrew, Paul and Gillian. They survive her, as do a younger sister, Ruth, and three grandchildren, Grace, Jemma and John.

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