AFIPS National Computer Conference and Exposition, June, Proceedings, pp. 21-29, New York. http://dl.acm.org/citation.cfm?doid=1499799.1499804 and to download paper https://www.computer.org/csdl/https://www.computer.org/csdl/proceedings/afips/1976/5084/00/50840021.pdfproceedings/afips/1976/5084/00/50840021.pdf The paper includes a long section on the Lyons/LEO story. From the abstract: “the paper also includes a detailed description of the birth and foundation of the most successful first British commercial computer company – Leo Computers Limited, and this gives an insight into the thinking which lay behind British early computer development”.
