Net worth: £9.35 billion
Age: Gerald Grosvenor, 64 (at the time of the ranking calculation). Hugh Grosvenor, 25.
When the ranking was initially calculated in April this year, the Sixth Duke of Westminster, Gerald Cavendish Grosvenor was near the top of the list. He made most of his money from inherited land that dates back to 1677. He owned the Grosvenor family estate, which has 300 acres across west London, including in wealthy areas like Belgravia and Mayfair. His property-development pipeline was also at £5.5 billion ($7.92 billion) as of the end of 2015.
However, in light of his death, his son Hugh Grosvenor (pictured) is set to inherit his estate.