The Sunday Times' annual list of the UK's super rich will be released next Sunday but some preview figures indicated that the London-based Hindujas have seen an estimated jump of 1.3 billion pounds in their fortunes.
Gopichand and Srichand Hinduja, who run the multinational Hinduja Group conglomerate with interests across automotive, real estate and oil, have a fortune of 11.9 billion pounds, according to the figures compiled by the newspaper.
Arsenal shareholder and Russian business chief Usmanov fell to the second place after his estimated fortune dropped to 10.65 billion pounds, followed by Kolkata-born Mittal in the third place with 10.25 billion pounds, registering a growth in profit from last year by 250 million pounds.
The list this year also revealed that London has more billionaires than any other city in the world and the number of billionaires living in the UK as a whole has risen to more than 100 for the first time.
There are now 104 billionaires based in the UK with a combined wealth of more than 301 billion pounds.
The British capital is home to 72 people whose aggregated family wealth tops 1 billion pounds.
The next most prosperous world city is Moscow, which boasts of 48 billionaires, just ahead of US cities New York and San Francisco.
"London is the financial centre of the world. It straddles time zones so they can come here and get the best financial advice. They like the culture, the tax regime is very nice for them and they feel safe here," says 'Rich List' author Philip Beresford, explaining London's supremacy.
For the first time this year, the world's super-rich needed a net worth of 1 billion pounds to make it to the Rich List's top 100 and a fortune of 1.7 billion pounds is now required to make the top 50 - up from 700 million pounds 10 years ago.
The Duke of Westminster is the richest Briton with around 8.5 billion pounds and is ranked 10th on the list.
Other notable figures in the top 25 include Chelsea Football Club owner Roman Abramovich (8.52 billion pounds),
Sports Direct owner Mike Ashley (3.75 billion pounds) and Virgin Group founder Sir Richard Branson (3.6 billion pounds).