Bruno Schroder, a merchant banker, is the first British entry in the new rankings - in joint 111th place - followed by Richard Branson in 173rd. The Schroder family, which controls one of the City's oldest and most prestigious merchant banks, is estimated to be worth pounds 1.7bn.
According to the list, which excludes dictators and royalty, Mr Gates, 42, is worth an estimated $51bn (pounds 31bn). Bill Gates hit the headlines last week after it was revealed that he was buying Cliveden in Buckinghamshire, one of the most famous stately homes and forever associated with Mandy Rice-Davies, Christine Keeler and the Profumo scandal of the Sixties. The Bill Gates consortium has offered pounds 42.8m for Cliveden and a group of properties which also includes Royal Crescent Hotel in Bath.
It is Mr Gates' fourth year at the top of the list. He has been ranked as the third-wealthiest person or private entity ever, beaten only by the Knights Templar and Napoleon Bonaparte. He has been estimated to earn around $500 (pounds 312) a second. He has also been reported as saying he will give away 90 per cent of his wealth during his lifetime.
The fortune of 47-year-old Virgin boss Branson is estimated at pounds 1.16bn, followed by the Rothschild empire, with a pounds 1.1b fortune and Sir Adrian Swire and Sir John Swire, who made their pounds 1.1bn fortune through shipping, aviation and soft drinks.
Bringing up the rear of the list are Associated Newspapers and General Trust boss Viscount Rothermere and Garry Weston, of Association British Foods, both with pounds 9.8bn.
Americans lead the rest of the list, with 12 entries in the top 20. They include the Walton family, which owns Wal-Mart Stores, at pounds 29bn; Michael Dell, boss of the Dell Computer Corp, at pounds 6.1bn; and the Haas family, which runs jeans giant Levi Strauss, at pounds 5bn.
The Top 10
Bill Gates, US, $51bn
Walton family, US, $48bn
Warren Buffett, US, $33bn
Paul Gardner Allen, US, $21bn
Oeri, Hoffman & Sacher family, Switzerland, $17.8bn
Quandt family, Germany, $15.3bn
Kenneth Thomson, Canada, $14.4bn
Forrest Edward Mars Sr and family, US, $13.5bn
Jay A and Robert Pritzker, US, $13.5bn
Prince Alwaleed Bin Talal Alsaud, Saudi Arabia,$13.3bn Lee Shau Kee, Hong Kong, $12.7bn
Theo & Karl Albrecht, and family, Germany, $11.7bn
Haniel family, Germany, $11.6bn
Curt Engelhorn,Germany, $11.5bn
Bettencourt family, France, $11.4bn
Steven Ballmer, $10.7bn
Gerard Mulliez and family, France, $10.3 bn
Michael Dell, US, $10bn
Li Ka-shing, Hong Kong, $10bn
Walter Haefner, Switzerland, $9.4bn
Emilio Botin and family, Spain, $9.2bn
Samuel Newhouse Jr and Donald Newhouse, US, $9bn
Philip Anschutz, US,$8.8bn
Cargill family,US, $8.8bn
Seydoux/Schlumberger family, France, $8.8bn