Ever since the revelation in 1953 that the finds at Piltdown were faked there has been very considerable speculation as to who was responsible for this astonishing fraud, and the matter has been ventilated many times in the last twenty years in our pages. Many people have thought that Charles Dawson was the forger and this seemed the answer by implication, though not specifically, in the late Professor Weiner's The Piltdown forgery. Other people, for various reasons, have tried to pin the blame, or part of the blame, on the late Father Teilhard de Chardin. Many other candidates have been put up and knocked down, and many of us have wondered whether we should ever know the truth. Now we think we do, owing to the most careful researches of Peter Costello, the biographer and literary historian based in Dublin. He has written an invaluable book setting out his complete investigations into this mystery, and coming to what we believe is the proper and final solution. In advance of the publication of his important book he has very kindly agreed to give us a short account, which we print here with great pleasure. All readers of Antiquity will look forward with avidity to reading the complete statement of his case in his published book.