Navinder Singh Sarao will never rank among the most notorious inmates of HM Prison Wandsworth. William Joyce betrayed Britain to the Nazis. Ronnie Kray ruled the ganglands of the East End. Bruce Reynolds masterminded the Great Train Robbery. Today Nav Sarao sits in a 10-foot-by-six-foot cell at Wandsworth, considered one of the worst prisons in Britain, accused of an altogether different sort of crime: helping to wipe more than $1 trillion off financial markets five years ago. At “Wanno,” a forbidding Dickensian fortress south of the River Thames, time moves to the same monotonous rhythm: the jangle of guards’ keys ... (full story)