The suburban streets of Cassiobury were laid out in the early 1930s on land that was formerly part of the estate of Cassiobury House, the ancestral seat of the Earls of Essex. The house, which originally dated from the reign of Queen Elizabeth I, contained lavishly decorated interiors and a substantial art collection and was surrounded by landscaped park land. Parts of the Cassiobury estate were sold for development land in 1908, and following the death of the 7th Earl of Essex in 1916, the family put the rest of estate up for sale in order to pay for death duties. Unable to find a buyer for the house, they had Cassiobury House demolished in 1927 and the estate was partly sold to Watford Borough Council to be used as a public park, with the remaining land sold to developers such as William King & Co and Charles Brightman for housing development.