Lex Greensill had a simple, billion-dollar idea - democratising supply chain finance. Suppliers want to get their invoices paid as soon as possible.

Companies want to hold off as long as they can. Greensill bridged the two, it's mundane, boring even, but he saw an opportunity to profit. However, margins are thin and Lex, ever the risk taker, made lucrative loans with other people's money: to a Russian cargo plane linked to Vladmir Putin, to former Special Forces who ran a private army, and crucially to companies that were fraudulent or had no revenue.

When the company finally collapsed it exposed the revolving door between Westminster and big business and how David Cameron was allowed to lobby ministers for cash that would save Greensill's doomed business. Instead, Credit Suisse and Japan's SoftBank are nursing billions of dollars in losses, a German bank is under criminal investigation, and thousands of jobs are at risk.