LEO IIn November 1951, J. Lyons & Co. Ltd. received the LEO I (Lyons Electronic Office I) computer, modeled closely on the Cambridge EDSAC, which the company had partly funded. The clock speed was 500 kHz, with most instructions taking about 1500 ms to execute, constrained by its paper tape I/O. Its ultrasonic delay line memory, based on tanks of mercury, was four times as large as EDSACs, with 1024 35-bit words.
Lyons used LEO I initially for valuation jobs, but its role was extended to include payroll, inventory, and so on; it was the first computer used for commercial business calculations.
In 1954, with the decision to proceed with LEO II and interest from other commercial companies, Lyons formed LEO Computers Ltd. LEO Computers Ltd was taken over by English Electric and this led to the breaking up of the team spirit that had inspired LEO computers. No new LEO designs were made and the organization eventually became merged with others to become ICT, eventually becoming ICL.
The LEO project were also pioneers in outsourcing, in 1956 they started doing the payroll calculations for Ford UK on the LEO I machine.
One of LEO I 's early tasks was the elaboration of daily orders which were phoned in every afternoon by thier shops and used to calculate the overnight production requirements. This, arguably, could be the first instance of a computer call center.