The aeronautical engineer Barnes Wallis (1887 - 1979) is but one of three civilians - Alan Turing and Churchill are the others - who have found a place in Britain's pantheon of the Second World War. His working life spanned the transition from horse and cart to hypersonic travel. Voted in a BBC poll as one of the hundred greatest Britons, he is remembered by the public as a softly spoken, slightly abstracted genius - portrayed by Michael Redgrave in the film The Dam Busters (1955) Richard Morris has spent the last fourteen years on a new biography of Wallis, who by the time of his death had become regarded, simultaneous, as 'Britain's most famous and most neglected engineer-inventor since Victorian times'. In this talk - parts of which will have a Yorkshire flavour - Morris will outline why and how the book came to be written, introduce newly accessible sources, and ask if there is truth in the received story of a patriotic genius who offered visionary ideas to his country and was snubbed by successive post-war governments. Indeed, if Barnes Wallis is Britain's most famous engineer of the twentieth century, what is his legacy?