Omid Scobie's new book Endgame sold just under 6,500 copies in Britain during its first five days on scale despite a blizzard of publicity - and has now plunged to 215 on the Amazon 'bestsellers' list. By contrast, Scobie's first book on the Sussexes, Finding Freedom, sold 31,000 in its first five days while Harry's autobiography Spare sold 467,183 - …