In November 1954 Lyons founded a new company, Leo Computers Ltd, to build and sell a new computer called LEO II. This had 1024 39-bit words of mercury delay-line store, backed by up to four drums and some magnetic tape decks. LEO II was first delivered in 1957 and about 13 were sold. This machine was followed by various versions of LEO III from 1962 onwards, about 100 of these finally being built.

In 1963 the data processing and control division of English Electric Ltd and Leo Computers Ltd came together as English Electric Leo Computers Ltd. In the next year English Electric bought out Lyons' share, thus ending a fascinating connection between teashops and computers!