Mike Platt, co-founder of the hedge fund Bluecrest, has a simple employment strategy. “I look for the type of guy in London who gets up at seven o’clock on Sunday morning when his kids are still in bed and logs on to a poker site so that he can pick off the US drunks coming home on Saturday night.” His instincts are right. A study has found that the best hedge fund managers are the keenest poker players.