According to The Sunday Times annual Rich List in which foreigners dominate, only one Briton has found place among the top five richest individuals.
The list will be published next Sunday. Philip Beresford, compiler of the Rich List said Mittal had the business sense of spotting the right kind of investment at the right time.
"It is absolutely extraordinary. He is an expert at spotting an industry and getting in there early, buying it cheaply and selling at a high price. That is the secret of his success and the only way to make money," Beresford, who has compiled the authoritative guide for the last 19 years, said.
Mittal's wealth was worth £14.9 billion last year but it has shot up to over £19 billion this year. Apart from Mittal, other foreigners in the top of the list include Russian magnate and Chelsea football owner Roman Abramovich, (about £10.8 billion) and The Duke of Westminster.
Mega-rich foreigners from India, Russia, France and other countries are attracted here by a generous tax regime, which allows foreign residents to be taxed only on what they actually brought into Britain -- regardless of how much money they earned overseas.
Beresford told the BBC: "London is such an attractive place for the very rich, not just tax wise but because they have the city, the culture and safety and security. 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."
According to Beresford, Queen Elizabeth has an estimated wealth of £300 million. But if the royal art collection and other assets are classed as belonging to her, she would be in the "top two or three" of the list.
The richest footballer in the world, David Beckham, has increased his wealth by 25 million pounds to 112 million pounds this year and is ranked at 619.
Virgin boss Richard Branson has dropped out of the Top Ten and is down from number nine to number 11 with his 3.1 billion £assets.
EasyJet's Stelios Haji-Ioannou is closing the gap on Branson, having broken the billionaire barrier. Stelios is now worth £1.29 billion and has moved up from number 80 on the list to number 49.
To get onto the 1,000-strong list, one must live in Britain and have personal wealth of about £70 million, compared with 60 million pounds a year ago.
When the rich list was launched in 1989, 75 per cent of those on it had inherited their wealth. But presently, 78 per cent of those on the list have made their money themselves through business.
