Posted: 14 March, 2022

Remembering Mary, Pioneering Computer Programmer and Esteemed Putney Alumna

Alumnae, General, In the Press, News, Senior School, Sixth Form

“I was very shy” Mary said, “so I didn’t stand out, I think, at all” – but it is so often the quiet ones you need to watch out for. Mary was a trailblazer and led a life which was, in every way, outstanding.

Mary Blood, as she was known when she joined Putney High School in 1938, would go on to become Mary Coombs; the first female commercial computer programmer on the world’s first business computer. She may have been shy, but she certainly did stand out.

Maths was Mary’s forte, “it was something definite – it was either right or wrong” and she excelled in it during her time at Putney. Years later she would go on to realise, while teaching at a primary school, that she had dyslexia. “Nobody knew anything about that in those days” she said.

World War II put a stop to Mary’s time at Putney as she and her fellow students were evacuated to Chippenham. “Of course, you got to know the teachers really well as we were quite a small group, so I have fond memories of Miss Achurch who taught Maths, and the games teacher, who also did guides.”

After leaving Putney, Mary, despite her passion for Maths, chose to read French and History at the then Queen Mary College, London. On graduating, Mary spent time teaching in Switzerland, something which she had intended to continue on her return to England in the summer of 1952.

She first worked at J Lyons and Co as a “holiday job” but was soon taken on by the company, progressing to a management trainee role, this providing her with the opportunity to join LEO. It was an office memo, inviting staff to join a “computer appreciation course”, which would lead to one of Mary’s most defining moments, her intrepid nature encouraging her to attend the course.

She was almost immediately offered a job as a programmer, “I jumped at the idea” she said. Only one other candidate to complete the course successfully joined LEO.

Mary was the only woman.

In 1953 electronic computers were not new, but LEO was the first to be designed for office work – it being entirely revolutionary to imagine a computer system designed for accounting, stock and cost control, statistics and payroll. “We were all engaged in a big adventure.”

Indeed, a big adventure, but also a huge challenge; the computer took up an entire room, and only provided 2 kilobytes of space, in comparison to the “umpteen gigabytes” of the modern-day computer.

Initially, Mary’s attention focused on payroll, not a small feat considering the 10,00 members of staff employed by Lyons and Co. She also took part in statistical work, the maths skills she had developed at Putney standing her in good stead. She worked on many test programmes, such as one for British Oxygen to develop “sales statistics by grid reference”.

It was not always plain sailing; Mary would often work well into the night with engineers trying to determine why a programme would go wrong. “You would sit at the control desk and you would try and analyse where exactly in the programme it was going wrong,” as the machine was based on thermionic valves, and, as Mary said, “valves are notoriously unreliable.” On one occasion it turned out (after months of trying in vain to discover why a machine wouldn’t work) to be the office lift that was interfering with the signals, there having been nothing wrong with the engineering to begin with.

Mary worked with LEO into the 1960s, before returning to teaching in 1973.

She kept in touch with her Putney classmates, her “closest friend” being a fellow Putney girl who she met in 1939. “She was new to Putney High School that term… and we have been close friends ever since.”

Mary Coombs, born February 4 1929, died February 28 2022


Read Mary’s obituary in The Guardian

Press enter or esc to cancel