Who's worth what
1. Bill Gates, 50, (US), 28.8bn from Microsoft
2. Warren Buffett, 75, (US), 24bn from Berkshire Hathaway
3. Carlos Slim Helu, 66, (Mexico) 17bn, telecoms
4. Ingvar Kamprad, 79, (Sweden), 16bn from IKEA
5. Lakshmi Mittal, 55, (India), 12bn from steel
Some of Britain's 24 billionaires in the Forbes list...
74. Philip and Cristina Green, 4bn, Bhs owners, second year at this ranking
100. Gerald Grosvenor, Duke of Westminster, 3.5bn
185. David and Simon Reuben, property investors, 2.1bn, new entry
245 equal. Barclay brothers, (1.6bn) and Sir Richard BransonJK Rowling, the Edinburgh-based author who made her fortune writing the Harry Potter books, fell to 746th position from 620th, with a fortune worth 576 million.
Bill Gates, the Microsoft co-founder, with an estimated fortune of 28.8 billion, took first place in the financial magazine's list for a record 12th time.
Mr Gates has donated significant amounts of his fortune to health programmes in Africa through the Bill and Melinda Gates Foundation, which aims to eradicate diseases such as AIDS and malaria.
Of the four other new Britons on the list, David and Simon Reuben, the brothers who founded a property investment empire, shot straight in to 185th position with an estimated net worth of 2.1 billion. Richard Desmond, the newspaper baron, tied with Mr Dyson.
James Ratcliffe, of the chemicals giant Ineos, joined the list in the 606th slot, with a fortune of 748 million. The five Britons bring the total of UK entries on the eagerly awaited list to 24.
For the second year in a row the wealthiest Britons were Bhs owners Philip and Cristina Green, who were in 74th position with a net worth of 4 billion.
The Duke of Westminster, Gerald Cavendish Grosvenor, was next, taking the 100th slot with a fortune of 3.5 billion.
David Sainsbury, the supermarket mogul, worth 921 million, slipped to 486th. Last year, ranked with his family, he was in 122nd place.
The Barclay brothers, former owners of The Scotsman, with 1.6 billion, fell from 160th to 245th place.
They were joined by Sir Richard Branson who last year ranked at 170th.
London had the third highest number of resident dollar billionaires with 23, while New York came top with 40, and Moscow second with 25. Luisa Kroll, Forbes' associate editor, presenting the 20th annual list at a news conference in New York, said: "A billion just isn't what it used to be."
Ms Kroll acknowledged the difficulty of the task since many billionaires refuse to cooperate, but defended the information, gathered by 30 reporters in seven countries, as unrivalled.
"Some people show us their spreadsheets showing the positive side of their business, so we have to ask what motivates them. Are they going to sell a business?" Ms Kroll said.
"Others are about to divorce and want to appear as being worth less. We always try to be on the more conservative side," she added.
The list is a source of great speculation and criticism each year, with some of those named laughing off the estimates of their net worth as wildly low or high.
This year has also seen a record number of billionaires on the list - 793 - up 15 per cent from a year ago.
Numbers have risen in India, Russia, Brazil and the Middle East. More women have also made it on to the coveted list - another ten bringing the total to 78.