David has written scores of best selling books on many aspects of psychology most of which have been translated into dozens of languages. His first book – written while he was still in his twenties - was aimed at redressing what he and his co-author considered a major miscarriage of Justice. Entitled Most Unnatural: An Enquiry into the Stafford Case (Penguin Press) created wide public interest and launched a campaign supported by, among other notable thinkers of their day, Bertrand Russell with whom David Lewis became friendly. He still does much of his writing from a desk left to him by the philosopher.

His second book, also a co-authorship, was a radical analysis of the British legal system entitled Just How Just? (Secker & Warburg, 1975). This too created a furore and drew David further into the public eye. To the satisfaction of the authors many of the changes they proposed in this book – such as taping interviews with suspects - were subsequently adopted by the British legal system.

A short time later he used his contacts in the Intelligence services, developed while working in Belfast, to write a book on sexual subversion. Entitled Sexpionage it became an international best selling and was made into a Hollywood movie.

An interest in the role of parenting in the developed of anxiety and stress problems during adulthood led to an intensive study of child development that resulted in a number of ground breaking books on the emotional and intellectual development of the child that became international best sellers.

These included: The Secret Language of Your Child; You Can Teach Your Child Intelligence; Mind Skills and How to Be a Gifted Parent. Other books for parents include Helping Your Anxious Child; Helping Your Child Through School; Your Child’s Drawings- Their Hidden Meaning.

In 1982, with co-author James Greene, he wrote Thinking Better for the New York publishers Rawson Wade. This rapidly became a best selling business book and a Fortune magazine Book Club Choice.

For Penguin he and his same co-author devised a series of fiendish tests designed to test every aspect of human mental functioning and entitled: Know Your Own Mind.

The Secret Language Of Success (1989) a practical guide to body language published in the UK by Transworld and in the USA by Carroll & Graf was also a best seller. In the US its popularity was helped by a national promotional tour, taking in twenty cities. Of this book Business Week wrote: “May well be the best book on the subject” while Advertising Age described it as: “Must reading for anyone entering or re-entering the job market.”

David’s professional interest in the relationship between stress and health led him to write a number of books on this important topic, including: The Doctors’ Heart Attack Recovery Plan (with medic Dr John Storey); One-Minute Stress Management; The Alpha Plan (made into a BBC TV documentary); Life Unlimited: Peak Performance Past Forty; Ten Minute Time and Stress Management and Information Overload - Practical Strategies for Surviving in Today's Workplace, published by Penguin Business Books in 1999.

His interest in, and personal experience of, the business world has resulted in many popular and practical books for managers and executives, including: The Soul of the New Consumer: Authenticity: What People Buy and Why in the New Economy. (With Darren Bridger). Of this book Tim Waterstone wrote in Management Today: “This is such an enjoyable, important and timely book…required reading.” Bookpage described it as: “…a lucid analysis of a wide range of sales related issues…For anyone in the business of sending those messages; it’s an enlightening and compelling guide.”

His most recent book: The Man Who Invented Hitler: The Making of the Führer recounts the life and death of a German psychiatrist Dr Edmund Forster who treated Hitler for hysterical blindness in 1918. The result of intensive research in Europe and America, this book as been described by one reviewer as: “An utterly absorbing book drawing upon profound wells of research”.