Welcome to LEO, the first business computer

This is the home of Swiss Rolls, Tea and the Electronic Office, our lottery funded project on LEO Computers.

In the late 1940s, J. Lyons and Co., the country’s largest caterer, made the prescient decision to invest, both financially and by offering staff support, in the computer developments being made at Cambridge University (EDSAC) on condition that they could copy their 'electronic calculator' if it worked.  From this collaboration came Lyons' own version, the Lyons Electronic Office (LEO), now acknowledged as the world’s first business computer.

While Lyons used EDSAC to base their own computer on, LEO evolved to become quite different to the Cambridge machine because it needed to perform in a completely different way for a completely different purpose. As a result, LEO computers played a key role in the early development of computing, and an even more important role in its subsequent social impact, which - just look around you now - turned out to be huge.

But the LEO story was not well known. Often dismissed simply as a copy of EDSAC in the established history of computing, such accounts have mostly acknowledged Lyons' contribution to history in only a very superficial way, recognising LEO as the first instance in which computing was applied to business processes, but little else. By bringing together, digitising, disseminating and researching a wide range of LEO-related material that had not adequately been addressed as a whole before, this project identified a myriad of ways in which LEO was groundbreaking.

It has been our pleasure to work in partnership with the LEO Computers Society (opens in new window), to preserve, catalogue and digitise their LEO artefacts, documents and personal memories. The Society work hard to ensure LEO's importance is recognised but prior to this project had no formal partner to work with, to ensure LEO's heritage was not lost forever. From the Centre for Computing history's perspective, for a museum to work with the very people who lived the stories we're telling, using the very artefacts we're preserving, has been a unique opportunity.

The project employed a variety of approaches to understand and tell the LEO story, and to ensure the accessibility of the new LEO archive. As a result we have galvanised a groundswell of recognition of LEO's rightful place in the history of computing, along the way raising public awareness and pride in this important, uniquely British heritage.

Find out more about the LEO Collections

Key outcomes:

LEO Film

Virtual LEO I


To keep updated on our progress, visit our blog

Browse the LEO Collections by Subject

With this project, we made safe internationally significant, historically important artefacts relating to the early Lyons Electronic Office (LEO) computers.

The LEO story is uniquely British, it pre-dates computing as we know it today and it straddles both computing history and British social history in a quite unique way, linking as it does with the Lyons teashops, prominent on high streets in the first half of the 20th century, especially in London, and with Lyons foods, from Lyons tea to Lyons Maid ice cream, that were ubiquitous in the UK for decades.

View our timeline of the development of the LEO computers.

The LEO collection at the heart of this project and that encapsulates this story includes:

1. Documents (correspondence, reports, photographs, schematics) recording technical developments in the early years of computing and their application to the business world and beyond. They focus on LEO but encompass and review many other early systems - none of the first generation of computers were developed in isolation - and, as LEO grew out of catering company Lyons, they incorporate important social history too. To see all the photos of used to create our Virtual LEO I, see our photo map.

2. Pieces of computer hardware, magnetic tapes and 'software' from the 1950s on. No LEO computers remain in the world today but bringing fragments that were previously privately held and therefore at risk of loss to a museum, together with the documentation, offered important detail about the birth, scale and impact of the machines.

3. Knowledge and stories. The LEO Computers Society has a membership of former LEO employees and enthusiasts (over 700 people at time of writing), mostly of generations whose memories of early business computing needed to be shared with others who have no idea how we came to create the kind of highly computerised society we have today. This has been achieved by collating and making public oral history interviews, as well as through the Society's contribution in helping the museum to understand the collection that has been brought together for the first time.

Lyons corner house

Prince Philip with LEO III


Leopedia logo

As well as the LEO collection, a key part of the project was also developing the Leopedia, a hub for all things LEO. Here we bring together sources of information on LEO, including both material that is held here at CCH and also signposting material held in other institutions or published in books, journals or via other media. Researchers and the public can now access all this material in one place.



The LEO Computers story is one of the ways in which the Centre for Computing History bridges the gap between the past, the present and our joint future.


A partnership project:
LEO Computers Society logo National Lottery Heritage Fund logo Centre for Computing History logo

Help support the museum by buying from the museum shop

View all items

Founding Sponsors
redgate Google ARM Real VNC Microsoft Research
Heritage Lottery Funded
Heritage Lottery Fund
Accredited Museum