Back in 2009 on an unseasonably warm autumn evening in Moscow, I was walking to dinner with a banker friend, a former British army officer with whom I’d bonded over a shared interest in history. At the time, we were both advising a large Russian bank which had recently listed its stock in London, and were irritated beyond measure to see its share price tanking, despite a booming Russian economy and it having no exposure to the American sub-prime mortgage market.