Rich lists are usually simple affairs: the more you have, the higher you climb. But the FT billionaires list is different. While enormous riches are necessary to gain entry, wealth alone does not guarantee a place on it. This list reflects the impact the world's most significant billionaires have on the rest of us.

Simply being the steward of a flourishing business empire, or quietly managing inherited wealth does not win a seat at the table. Writing out a cheque and mumbling a few words about "putting something back" before immediately disappearing will not do either.