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The Centre for Computing History, Cambridge, our partners for the LEO Heritage Project, has had to close its museum to all visitors. CCH depends on school and individual visits for nearly all its income. If you visit their website at 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.


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.
In 2018, The Society formed a partnership with the Centre for Computing History in Cambridge and together we gained important funding from the National Lottery Heritage Fund. We are working on a joint project called 'Swiss Rolls, Tea and the Electronic Office: A History of LEO, the First Business Computer.' So far, we have gathered together a large amount of LEO memorabilia - much of it from generous members. Our partners in Cambridge have archived this material and are working on digitising it.
Our comprehensive catalogue of all material related to LEO - LEOpedia - is also being incorporated into the project. We aim to establish a single window on to all LEO collections wherever they are - our archive includes artefacts, written and oral memoirs, documents, engineering drawings - in fact, anything LEO-related. We are also planning exciting new ways to tell the LEO story - for example, by creating a virtual reality (VR) version of LEO I.
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We are very grateful for this lottery funding and are now together bidding for a further phase so that we can carry out our ambitious aims to make the LEO story come alive.
The importance of LEO has been recognised by displays in many prestigious institutions such as the Science Museum, London, the National Museum of Computing at Bletchley Park, the Centre for Computing History, Cambridge and as far away as Mountain View, California. There are historic LEO materials held in several universities and archives including those at Manchester, Warwick, Melbourne University and the Charles Babbage Institute, USA. Oral histories of LEO pioneers and practitioners are available to listen to on websites such as that of The British Library.

Other activities of the Society include:
  • supporting a PhD student at Middlesex University
  • promoting LEO lectures
  • arranging talks on LEO to clubs and societies
  • organising reunions/exhibitions
  • publishing a regular newsletter 'LEO Matters'
  • selling copies of books on LEO - by Peter Bird, Georgina Ferry - and an anthology of reminiscences of those who worked on LEO themselves
Please look at the News section of this website for up to date information on our activities.

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!
To join please see the Application Form on the drop down menu. Membership is currently free of charge. Contact for any further information
A comprehensive collection of references and holdings related to the story of LEO has been compiled by Frank Land, FBCS.   Now known as the LEOPEDIA and currently at 112 pages, it is regularly augmented. The areas covered are shown below in a clip from the Contents page of the LEOPEDIA.
The latest PDF version (04/11/20) is available here...The Cambridge Computer History Museum (CCH) now holds an HTML version of LEOPEDIA, fully searchable and linked also to other LEO assets in their care and to other LEO collections. This will in due course supersede the PDF version and it can be accessed here...


Newsletter for Autumn/Winter 2020
A PDF version can be read or down–loaded  LEO Matters Note the contents list is now linked to the articles. Just Click on a contents line and you will be taken to the article without having to scroll down the document. Also the ICL All Stars Magazine Issue 20  Issue 20