Leo Computers Ltd. was formed in November 1954, as a result of a decision by UK catering business J. Lyons & Co. to use computers in their commercial operations (J. Lyons & Co. operated tea shops from 1887 - 1998).

The company developed a computer, called Lyons Electronic Office (LEO), based on EDSAC, a computer developed in Cambridge. EDSAC was adapted from a machine designed for technical calculations into one suitable for business data processing.

Leo Computers merged with English Electric 1963; later English Electric-Leo then English Electric-Leo Marconi then English Electric Computers; incorporated with International Computers Limited (I.C.L.) in 1968.
LEO I  and LEO II used mercury delay line memory; LEO III used ferrite core memory.

LEO IIIs sold in Australia
Tubemakers Pty Ltd Sydney 1963-76
Shell Australia Melbourne 1964-69
Shell Australia Melbourne 1966-72
Colonial Mutual Life Melbourne 1964-73

The core memory (ST 029038) in Museum Victoria's Collection was purchased from United Trade Sales. 


Wikipedia. Accessed 16 May 2013. http://en.wikipedia.org/wiki/LEO_computer

The Staffordshire University Computing Futures Museum LEO Page. Accessed 26 April 2013. http://www.leo-computers.org.uk/leo-3s.html

LEO 3. Accessed 16 May 2013. http://www.leo-computers.org.uk/leo-3s.html

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