Bill Gates, the IT tycoon and philanthropist worth $66 billion, is the richest man in the US, according to the latest Forbes Rich List, with renowned investor Warren Buffett in second place, at $46 billion.

In third place is another giant of Silicon Valley, Larry Ellison, worth $41 billion; in fourth, is Charles Koch, at $31 billion, and fifth is his brother, David Koch, at $31 billion. The Koch brothers made their fortunes from diverse sources and are renowned, among other things, for their financial backing of political organisations and think tanks.