Preface When A D Blumlein and two of his colleagues were killed in an accident@ in June 1942@ the Daily Telegraph referred to Blumlein's death as a 'National loss'; Air Chief Marshal Sir Philip Joubert described the accident as 'a catastrophe'; and the Secretary of State for Air@ Sir Archibald Sinclair@ wrote that 'it would be impossible to over-rate the importance of the work on which they were engaged'@ their loss was a 'National disaster'. Blumlein's contributions to radar were of crucial importance to the war effort and undoubtedly saved thousands of lives. The abandonment@ in the spring of 1941@ of the German 'Blitz' attacks on British cities and towns; the AA gunnery defence of the United Kingdom; the achievement of victory in the Battle of the Atlantic; the transformation of the bombing offensive over Germany; and the air offensive against Axis shipping in the Mediterranean Sea in the autumn of 1942@ all owed much to the endeavours of Blumlein. By any definition he was a genius. During his short working life from 1924 to 1942 Blumlein's work ranged over the fields of telephony@ electrical measurements@ monophonic sound recording and reproduction@ stereophonic sound recording and reproduction@ high-definition television@ electronics generally@ antennas@ cables and radar. After his death Mr I Shoenberg@ who was the Director of Research at Electric and Musical Industries Ltd@ where Blumlein had been employed from 1931@ said: 'There was not a single subject to which he turned his mind that he did not enrich extensively'. Nevertheless@ although Blumlein did much to enhance the well-being of society@ his name is not widely known to members of the general public. Attempts to write a biography were made from 1967/8 and 1971/2 but without success. The task of writing a biographical account of Blumlein's life and work has not been easy for several reasons. EMI@ pre-war@ discouraged its staff from publishing papers ?? Blumlein's publication list comprises just two learned society papers. No collection of personal letters exists and there is a paucity of information about his private life. Moreover@ most of his coworkers@ friends and colleagues are now dead@ many of their earlier recollections have not been available to the author@ and Blumlein lived for just over half the biblical three-score years and ten; he was 38 years of age when he was killed. Fortunately he applied for@ and was granted@ 128 patents from 1927 to 1942. These@ together with various unpublished internal reports@ memoranda and letters@ published papers@ family records and taped reminiscences of some of his associates@ have enabled an account of the greatest British electronics engineer of the twentieth century to be written. Much care has been taken to ensure that the material presented is accurate. Primary source documentation has been used@ where possible@ throughout the book and extensive reference lists have been prepared. Unreferenced biographies/histories must always be read with a degree of circumspection: people's memories are not always infallible; sometimes a person's recollection can have been influenced by what he or she has read or heard between an event and the recall; and it is possible that a person may wittingly@ or unwittingly@ exaggerate his or her importance in the saga of events. Special pains have been taken on the chapters which describe Blumlein's radar work@ since several unreferenced or poorly researched autobiographical books by some former radar workers have been published which contain errors. A great deal of time has been spent by the author in the Public Record Office researching its very extensive radar collections@ and detailed source references have been quoted. The work of Blumlein was@ of course@ highly technical in character and many of his patents are very complex. Their detailed description is not appropriate for a general account of his life and times. However@ this book would not be complete without some mention being given of his contributions. These have been broadly considered in the text@ but several technical aspects (which may be omitted by the non-technical reader) have been dealt with in the technical notes which accompany several of the chapters@ and in Chapter 14.