Just over a decade ago, a british banker made a small piece of financial history. At the time, Robert Reoch was working as a trader in JPMorgan's London office. Like most of his peers, he spent his days on the phone, surrounded by computer screens, trying to cut deals with clients across Europe. But one day an unusual trade crossed Reoch's desk: one of his clients wanted to buy a contract which would effectively protect him from the chance that any one of three government bonds might turn sour. “It was the first time we had done a transaction like that - I guess you could call it one of the first credit derivatives,” Reoch proudly recalls, noting that the trade was so “cutting edge” that the team only sorted out the legal documentation several weeks later.

Since then, Reoch has left the City dealing floors for the quieter surroundings of a Dorset farmhouse. But his dance with financial innovation continues: he spends part of his time in Mayfair, running a consultancy business that advises clients on how to navigate the “credit derivatives” world that he helped create. This area of finance has exploded at such speed that outstanding trades are now put at more than $60,000bn (or, for comparison, 20 times the aggregate capitalisation of London's equity market).