The palatial residence, on a street dubbed Billionaires’ Row, is believed to have been bought by Britain’s richest man, steel tycoon Lakshmi Mittal. He is believed to be close to exchanging contracts with owner Noam Gottesman, a US-born financier. The home in Kensington Palace Gardens, West London, Princess Diana’s former street, is being sold furnished and with an art collection. It works out at an astonishing £8,000 per square foot. Mr Mittal, who denies being the buyer, has been looking to splurge some of his £27.7billion fortune on a home for son Aditya, 32. Mr Mittal moved into the half-mile, tree-lined private avenue four years ago after paying £67million for a 12-bedroom home. His new pad pips the £115 million previous record – paid in March for a flat being built in nearby St James’s Square.