This is the Website of the LEO Computers Society, Celebrating the Worlds First Business Computer.


It was, surprisingly, a British catering firm, J. Lyons and Co – famous for their teashops, Swiss rolls and ice cream which pioneered the development of computing for commercial applications. As the Guinness Book of Records ratifies, Lyons Electronic Office (LEO) was the first business computer in the world.

In 1951 the LEO I computer was operational and ran the world’s first regular routine office computer job.

The LEO Computers Society (which has charitable status) started life as a reunion society for people who worked on these remarkable machines. Its principal mission now is to ensure that LEO’s heritage is preserved, protected and – importantly – promoted to wider audiences. Read more about the LEO Computer Societies mission (Our Mission).

Introducing Zoom Online Meetings for LEO Computer Society Members. See the Announcement

Cambridge Centre for Computer History, our Partner for the LEO Heritage project, has had to close it doors to visitors due to the Covid 19 pandemic. CCH depends on school and individual visits for nearly all its income. If you visit their website (CCH Website) you will see that they are appealing for donations to help sustain them. We hope that members may be able to offer some support to our partners in these difficult times.
There is also a Project Blog which provides more insight into the activities and challenges. To view click (Project Blog).

ICL AUSTRALIA NEWSLETTER Issue 69 August 2020.Issue 69

URGENT REQUEST: Do you have any LEO memorabilia – e.g. pieces of hardware, engineering drawings, charts and plans, programming information, computer files, correspondence or reminiscences?
If so, you can help us. We are collecting such material to join a growing archive at the Centre for Computing History in Cambridge, our partners in a National Lottery Heritage funded project to preserve, protect and promote the history of the world’s first business computer.
Please contact the Secretary@leo-computers.org.uk for further details.

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Become a member

Membership of the Society is open to:

  • all ex-employees of LEO Computers and its succeeding companies;
  • anyone who worked with a LEO computer;
  • and indeed anyone who has an interest in the history of LEO Computers.

We welcome the active participation of members – whether through volunteering as interviewers for oral histories, writing their own reminiscences, contributing to the newsletter or simply through spreading the word!

Join today

Membership is currently free of charge. Contact Secretary@leo-computers.org.uk for any further information.