Mary Blood (Mary Coombs)

Mary Blood (Mary Coombs)

Born 1929

Mary Coombs (nee Blood) was the first woman to work on the Lyons Electronic Office (LEO) computers. She didn't take the typical route to becoming a computer programmer; she earned a BA Honours degree in French from Queen Mary University in London and then took a holiday job at Lyon’s, the well known catering company with a chain of tea shops (known as Lyon’s Corner Houses) throughout the UK. Despite not studying maths formally, her maths skills led to a place with Lyons’ Statistical Office and there Mary learned of an opening with the department working on the LEO computers.

LEO was the world’s first computer used exclusively for business applications. Mary completed Lyons’ ‘computer appreciation course’ with a stellar performance that led to an offer of a job in the computer division with Frank Land, working on the LEO from 1952 on. 

Mary worked on programming the LEO to handle payroll. She is recognised as the first female commercial programmer. She became a supervisor and worked to locate and repair coding errors in the programs created by others. She worked on the LEO I, II, and III and her experience led to her being in charge of rewriting the programs from LEO II to be used on LEO III. She went on to work for English Electric Leo Computers and International Computers Limited as these companies eventually merged.

Mary Coombs was one of the women profiled in our Women in Computing Festival 2017 of entitled Where Did All the Women Go?. Click here for the Women in Computing timeline created for that event.

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