CW@60: Being there at the start of business computing
Former LEO programmer Peter Byford reflects on working with the world's first business computer
By
Peter Byford
Published: 27 Jul 2026
On 22 September 2026, Computer Weekly turns 60. To mark the milestone, we asked some of our friends - experts, parliamentarians, IT leaders and suppliers - for their perspectives on how tech has changed their lives over six decades. What's changed the most for you since then?
Today we live in a society fuelled by technology. Consider what life was like when a computer was something only a select few scientists and researchers had access to and the internet and networking were still years away from being developed.
In the late 1940s, one British company played a pioneering role in getting it all started.
The LEO 1 – short for Lyons Electric Office - is in the Guinness Book of Records as the world’s first business computer. It was developed to run internal orders and payroll for J. Lyons & Co, which was once Britain’s largest food and catering chain.
The company saw the potential to fund the development of a digital computer based on Maurice Wilkes’ Cambridge University EDSAC (Electronic Delay Storage Automatic Calculator), which led to the creation of the LEO 1 and later a computer bureau service, which is how I first encountered this amazing machine.
In mid-1961, I decided to leave school. I had interviews and a number of job offers mainly from insurance companies, which all seemed fairly boring. My father spotted an advert in the Evening Standard for LEO Computers, which was looking for trainee computer programmers.
An introduction to programming
I had little idea what a computer was nor what a programmer was, but I thought that sounded interesting. I had an aptitude test, which was a brief introduction to programming code - apparently LEO 2 code - in the morning and lunch. As I recall, in the afternoon I had to code a brief program to make a cup of tea. I enjoyed doing it and was one of three people who were offered jobs.
The office was in Bayswater with its local Indian and Chinese restaurants - cuisine I hadn't experienced before. There were a lot of pranks, such as the time I took a nap in the toilets and the LEO operators stole my trousers and locked me in the cubicle. There were plenty of long nights and we had to make technical compromises due to the limits of those early machines.
One of the early programs I worked on was for a share index programme for Courtaulds, which was used at the time of ICI’s attempt to take-over the textile manufacturer. ICI bought a very large amount of Courtaulds shares. - the number of shares was so large that I couldn't calculate it in the program. I had to enter the actual dividend into the program code. You had to do things like that.
Looking back at LEO, it had its first run in November 1952, processing a weekly valuation of bread and cakes for J. Lyons & Co
Peter Byford
Lyons had annual sports days when all 20 or so parts of the company were involved. Each department and parts of the company competed in one of 10 or so games. In 1964, somehow I was the organiser of the LEO team who won the pennant.
After Lyons decided to merge its LEO Computers business with English Electric, a few of us felt the company would never be quite the same. So, I moved on and did various programming and systems jobs up until 2004 when I retired.
LEO reunion
In 1978 Roy Farrant, a LEO operating shift leader at one time, organised the first full-scale reunion of LEO people at The Rugby Club in London. He organised the second one in 1981, where he “passed the baton” to me. I had four helpers and we formed the LEO Computers Reunion Society. Reunions were held every three years in the early days.
In 2018 we formed a partnership with the Centre for Computer History in Cambridge. The LEO Computer Society also became a registered charity which helped us gain a grant from the National Lottery Heritage fund to support the development of a virtual version of the LEO 1.
Like everyone in the computer industry, we lived through the Y2K millennium date bug, because the old computer systems stored only the last two digits of dates. During my time working on the billing systems at British Gas, there was a sort of sheer panic from some people as to what the hell was going to happen.
I think a lot of money across the computer industry was spent on preparing for Y2K in case all the computers fell over - but basically, they didn't in most cases. There were one or two mishaps, but nothing really happened because we’d done a lot of the preparation work.
Personal computers
From big central computers and mainframe systems, I first encountered a personal computer when I worked at Eastern Gas, which was part of British Gas.
As information manager, I had to look at what personal computers were available. There were quite a number of different types and I remember going to Esso to talk to its information manager to ask which PC he used. It was the IBM PC that Big Blue had recently launched, which ran an operating system from a little software house called Microsoft. Although many of the other personal computers were far better than IBM, the companies that offered them wouldn't have been able to sell enough to meet demand from business, which is, of course, exactly what IBM was able to do.
Looking back at LEO, it had its first run in November 1952, processing a weekly valuation of bread and cakes for J. Lyons & Co. This November is the 75th anniversary of that first run and the LEO Computer Society is organising a number of events and activities to commemorate this significant moment in the evolution of business computers.
Peter Byford has chaired the LEO Computer Society charity since 1981, when it was known as the LEO Reunion Society.
