London’s Mayfair Is the World’s Priciest Ultra-Prime Market

London’s Mayfair neighborhood beats Manhattan as the most expensive ultra-prime market in terms of price per square foot, according to a February report by Beauchamp Estates. In its fourth “Ultra-Prime Barometer” report, the London-based luxury residential brokerage said the average per-square-foot price for Mayfair ultra-prime homes has reached £3,853 US$4,812,…