HONGKONG magnates have rocketed up the scale of British wealth over the past year with the Swire brothers now rated the fifth richest people in the country. The Sunday Times league table of Britain's richest people, extended to cover 400 in 1993, was published yesterday still showing the Queen as the wealthiest person in the land, despite the recent rows over the size of her estate and her decision to pay income tax. The paper has marked her fortune down though - from GBP6.5 billion (HK$76.5 billion) last year to GBP5 billion now. Second come food packaging giants Gad and Hans Rausing, almost unheard of even in Britain, third supermarket boss David Sainsbury and his family and fourth Associated British Foods chief Garfield Weston with GBP2.1 billion. But Sir John and Sir Adrian Swire are estimated to now be worth GBP2 billion compared to a more modest GBP600 million last year. ''The leap in the Swire fortune results from the huge increase in the profits of John Swire and Sons, the Hongkong-based conglomerate, two-thirds owned by the Swires,'' said the survey. ''With after-tax profits in the year to December 1991 of GBP350 million the group could command a high price tag in excess of GBP3 billion, despite its high levels of borrowings. This would value the family stake at GBP2 billion. ''Though changes in accounting rules have contributed to the increase in profits, Swire's Hongkong operations have been performing spectacularly well. ''Its Swire Pacific business produced a 101 per cent increase in profits in the first half of 1992 to US$282 million, while Cathay Pacific, Swire's highly-regarded airline, showed it had recovered in the downturn in trade caused by the Gulf War with a 13per cent rise in profits.'' The Keswick brothers have also shot up the league from 57th last year to 29th today with a fortune estimated at GBP260 million compared to GBP168 million in 1992. ''Jardine Matheson, the Hongkong conglomerate run by the Keswick family and its sister company Hongkong Land, have benefited from the boom in the colony,'' the survey said. ''The family was also active in London last year and bought 30 per cent of Trafalgar House, the troubled property and construction group. ''The Keswicks are not without strong city connections of their own. A third brother - 'Chips' Keswick - is chairman of Hambros Bank and was knighted in the New Year's Honours list.''