Only one of Britain's five wealthiest people was born in the UK, according to the Sunday Times Rich List 2007.
The high price of steel has sent Mr Mittal's wealth soaring
The £19bn fortune of Indian steel magnate Lakshmi Mittal ensured he kept his title as Britain's richest person.
The Duke of Westminster was ranked at number five in the list behind four non-Britons, including Chelsea owner Roman Abramovich who is worth £10.8bn.
Analysts said a growing number of mega-rich foreigners are attracted to the UK by a generous tax regime.
As well as Russia and India, the wealthy from Scandinavia and France are also looking to base themselves in the UK.
There were several reason why the UK was a big draw, said the list's compiler, Dr Philip Beresford.
"London is such an attractive place for the very rich, not just tax wise but because they have the city, the culture and the safety and security," he told the BBC.
"And New York has shot itself in the foot with its onerous regulation.
"There is also general paranoia in the US after 9/11 that makes foreign billionaires feel uncomfortable, and London is winning as a result."
Ernst and Young tax expert Patrick Stevens said that the real draw was a tax regime allowing foreign residents to be taxed only on what they actually brought into the UK - regardless of how much money was earned overseas.
"It's a very attractive regime compared to other parts of the world," Mr Stevens told the BBC.
Roman Abramovich's divorce "barely dented" his fortune
"Every few years the subject comes up about whether its right to have a separate tax regime for people from overseas who come to live here, but nothing has happened and there's no immediate sign of it changing."
The money which did come in was a "boost for the economy", he added.
"If we didn't have the regime they wouldn't come and it's income from around the world that we wouldn't get a sniff of otherwise."
Full details of the 2007 Sunday Times Rich List have not yet been released but it is expected to include about 65 billionaires - up from 54 last year.
To get onto the 1,000-strong list you must live in the UK and have at least £70m, compared with £60m a year ago.
When first launched in 1989, 75% of those on it had inherited their wealth.
Today, 78% of those on the list have made their money themselves through business.
However, fewer than 10% of those on the rich list are women.
Stelios takes off
The continuing high steel price has helped Mr Mittal, whose Mittal Steel bought rival Arcelor last year boost his wealth from the $14.8bn he had last year.
Meanwhile, a costly divorce settlement with his wife Irina had "barely dented" Mr Abramovich's fortune, Dr Beresford said.
Climbers include Easyjet's Stelios Haji-Ioannu in 49th place with a personal worth of £1.29bn, singer Robbie Williams, ranked 755th with £95m, and David Beckham, placed 619th with £112m.
X Factor and American Idol judge Simon Cowell saw his wealth balloon by £40m to about £100m.
Sir Richard Branson slipped two places to number 11, with his £3.1bn fortune.
The Queen has an estimated wealth of just about £300m, Dr Beresford said.
But he added that if the royal art collection and other assets had been classed as belonging to her, she would have been in the "top two or three" of the list.