In 1948 the Estate, then valued at £10 million, was subject to death duties of £7.6 million on the death of the seventh Viscount Portman, resulting in the sale of all the family’s West Country estates as well as the northern part of the London Estate in 1951, and the area around Crawford Street the following year. In the later 1950s and 1960s the Estate collaborated with the developer Max Rayne to redevelop the frontage of Oxford Street and Baker Street, as well as the south and west sides of Portman Square.