Photos: The world's first business computer turns 60

Taking tea with the Leo...

The world of business today would collapse without computers to make sure staff get paid and customers receive their orders.

Enterprise's love affair with computing can be traced back to this machine, the Lyons Electronic Office or Leo I.

Leo's first task was working out how much it cost Lyons to get buns, tea cakes and other baked goods from its bakery into its national chain of tea shops - a far cry from the multibillion-pound financial transactions trusted to corporate machines today.

If Leo's first task sounds menial that's because it was. Before the computer came along it required clerks to crank through the many calculations, exactly the sort of boring and repetitive task that was ripe for automation.

That very first business application was fired up 60 years ago on Thursday, and today computer conservation enthusiasts gathered at London Science Museum to mark the anniversary at an event supported by Google.

Leo was a whale of a computer, weighing in tonnes and taking up some 5,000 square feet at Lyon's headquarters in Cadby Hall in Hammersmith, as seen here.

Not that Leo was especially large by the standards of the time. In 1951, computers were built using vacuum tubes or valves - glass tubes resembling light bulbs - that allowed them to process information. Almost 6,000 valves throbbed away inside Leo carrying out calculations, while 64 five-feet-long mercury tubes acted as its memory. Punched tape or card was used to feed data into Leo and to record its findings.

Leo was notoriously flaky at the start of its life - some 50 valves had to be replaced each week - but by 1953 Leo had proven to be so capable that Lyons gave it a new job: calculating the company's payroll.

By 1953, Leo was putting human mathematical calculators in the shade - able to calculate an employee's pay in less than two seconds compared to the eight minutes-plus it took a clerk.

Above, Lyons employees look at a circuit diagram during Leo I's construction.

Leo I proved so useful to Lyons that its successors, the Leo II and III, were sold to other organisations such as the post office and Ford motor company - introducing the world of business to the power of computing.

Pictured is a close-up of the control desk for the Leo I.

Despite its stature, Leo I's computing muscle couldn't begin to compete with the power of modern computers. Comparing processing speed alone, Leo I would be some 2,000 times slower than an iPad 2 and sucked up thousands of times more electricity.

Here is a shot of Leo I's decimal-sterling binary converter.

Lyon's technicians were inspired to build Leo by the Edsac - an early stored program computer that was built at the University of Cambridge in 1949.

Above is the printer-tabulator for the Leo I.