The long and fruitful career of the Ghanaian con-artist John Ackah Blay-Miezah suggests that the adage “there’s one born every minute” may be a serious underestimate. In his heyday, Blay-Miezah was the world’s most successful fraudster, persuading thousands of people to invest in his schemes even though he couldn’t have been more patently dodgy if he’d had “Catch Me If You Can” tattooed on his forehead.  In 1974, while serving a sentence for fraud, Blay-Miezah devised his masterpiece, the Mona Lisa of scams. He managed to secure a meeting with Ghana’s military dictator General Acheampong, and told him that he had been a friend from youth of the deposed ex-president Kwame Nkrumah, who had died in exile in Bucharest two years earlier.…