With its history dating back to 1677, the group is known for developing the affluent London neighborhoods of Mayfair, Belgravia and Pimlico. It’s now a global firm with £9.5 billion of assets under management across 48 cities. Hugh Grosvenor, its 35-year-old owner and the seventh Duke of Westminster, has a net worth of about $12.7 billion, according to the Bloomberg Billionaires Index.