Over the past year alone, their fortune has jumped by £1.356bn.
Mumbai-born siblings David, 80, and Simon, 77, with interests across property and internet, have been on a buying spree, taking hold of £1billion of London property a year ago.
The list reveals that retailer Sir Philip Green has lost his billionaire status; his fortune is believed to have halved in a year because of a pension black hole in his Arcadia empire.
London-based Sri and Gopi Hinduja, of the sprawling Hinduja Group of companies, have a fortune worth £22 billion (S$39 billion), up £1.4 billion on a year ago. The Mumbai-born siblings snapped up a range of lucrative properties in London over the previous year, including affluent Mayfair's £300m Burlington Arcade and Shoreditch's Curtain hotel. The two moved to London in 1979 to develop the export business. The renowned steel magnate suffered losses to the tune of 3.99 billion pounds during 2018, which caused his fortunes to take a hit.
The list, which estimates the 1,000 richest people in the United Kingdom, is based on identifiable wealth including land, property, other assets such as art, and shares in companies, the Sunday Times says.
Meanwhile, Sir Philip Green and his wife Tina are placed at 156th on the list, down from 66th past year.
Cardiff-born venture capitalist Sir Michael Moritz remained Wales' richest person with a 3 billion pounds fortune.
Ed Sheeran earned more during 2018 than any musician has in a single year, pushing his fortune up to £160m, making him fifth in the list.
Industrialist Swraj Paul and family are placed 69th with a wealth of £ 2 billion. It does not include the amount contained in people's bank accounts, though. India has 76 billionaires, according to the Sunday Times.
Robert Watts, compiler of the list, said: "On the face of it this looks like a bumper year for the super-rich, with record wealth, more billionaires and the entry level rising to £120m".
The wealthiest woman in Britain is Sigrid Rausing, granddaughter of the man who invented the Tetra Pak packaging fortune.