Born in Aberdovey, he spent his childhood in Wales and was educated at Christ College, Brecon (1941–49). He spent two years in the RAF (1950–52),and worked as a science journalist and writer until 1957 when he began a B.A. course in Psychology at University College, London, graduating with honors in 1960. After a summer fellowship at Duke University, where he first met his future American wife, Nancy Fullmer, he took up a Research Assistant post in the Physics Laboratory, University of Reading, working on eye movements under Professor R.W. Ditchburn. Upon receiving his PhD (the title of his thesis was “Pattern Perception and the Stabilised Retinal Image”), he went to the Division of Computer Science, National Physical Laboratory, Teddington in 1964, where he remained until his death of cancer in 1979. Survived by his wife and two children Christopher Samuel Evans and Victoria Evans-Theiler.
In 1979, he wrote a book about the oncoming microcomputer revolution, The Mighty Micro: The Impact of the Computer Revolution (London: Victor Gollancz Ltd, ISBN 0-575-02708-8), which included predictions for the future up to the year 2000. This book was also printed in the USA, but called The Micro Millennium (New York: The Viking Press, ISBN 0-670-47400-2). He subsequently scripted and presented for the commercial television company ATV a six-part television series based on this book and broadcast posthumously by ITV between October and December 1979.
In the 1970s, Evans undertook a set of interviews with computer pioneers such as Konrad Zuse and Grace Hopper. These were released through the Science Museum, London, as a set of cassette tapes, collectively entitled Pioneers of Computing.
Dr Evans also edited two anthologies of psychological science fiction/horror stories, Mind at Bay and Mind in Chains, a collection of science writings, "Cybernetics: Key Papers," a reference book "Psychology: A Dictionary of Mind, Brain and Behaviour," and was a contributing editor to the science magazine Omni. A passionate flier, and former pilot in the RAF, he also edited a yearly pilot's diary of rural airfields in Great Britain.
Dr Evans died of cancer in 1979 at the age of 48, shortly after The Mighty Micro had been published in hardcover.