Lex Greensill is an Australian success story, a one-time farmer turned billionaire financier who flies on private jets and flits between New York, London and Sydney. Greensill, the eponymous business he launched eight years ago, says it has provided more than $50bn of financing to millions of businesses around the world. It has a multibillion-dollar partnership with Credit Suisse and lists blue-chip companies such as Vodafone, Coca-Cola and General Mills among its clients. Former UK prime minister David Cameron is an adviser to the firm and Lex Greensill has been honored by the Queen for his services to the economy.

But there is another side to the rise of the 42-year-old finance whizz, one marked by controversy. It has culminated in Greensill’s role in the events that led to the near collapse of a key partner, GAM, a Swiss investment firm that manages around $130bn in client assets, whose share price has fallen about 80% in the past year. Several former colleagues and others who have worked closely with the Australian banker say Greensill is charming and persuasive, but that he is also an aggressive risk taker.