The aim of this book is to trace from early days the development of a mathematician and scientist of great originality and to record details from which a selection may be made by a future biographer. Owing to the enforced silence regarding my son's activities in the Foreign Office during the Second World War, there is, except for some few anecdotes, a regrettable gap of six years in the narrative. The book is divided into two parts. The former and major part is mainly biographical but contains sufficient scientific material to indicate the scope and depth of my son's research. The second part affords more technical particulars which might prove wearisome to the general reader: but these barely touch the fringe of his work on Computing Machines and Morphogenesis. His writings on these and other subjects, together with a posthumous paper on Morphogenesis, prepared by Dr. N.E. Hoskin and Dr. B. Richards, can be studied in the volume of his collected works, which is to be published by the North-Holland Publishing Company, Amsterdam. I am indebted to many of my son's friends – too numerous to name – for their recollections. Here I take this opportunity to express my gratitude to various American mathematicians and scientists for their particularly courteous interest and co-operation. For their scrutiny of my typescript and valuable suggestions and advice, my special thanks go to Professor M.H.A. Newman, F.R.S., Mrs. Newman (Lyn Irvine), Mr. Geoffrey O'Hanlon and to Mr. Nowell Smith, who also read the proofs.