Grim's Dyke (sometimes called Graeme's Dyke until late 1891) is the name of a house and estate in Harrow Weald, in northwest London, England. The house was built from 1870 to 1872 by Richard Norman Shaw for painter Frederick Goodall and named after the nearby prehistoric earthwork known as Grim's Ditch.
The house is best known as the home of the dramatist W.S. Gilbert, of the opera partnership Gilbert and Sullivan, who lived and farmed there for the last two decades of his life. He died while attempting to save a girl from drowning in his lake. Lady Gilbert and the Gilberts' ward, Nancy McIntosh, lived there until her death in 1936. The statue of Charles II now found in Soho Square stood on the property from about 1880 to 1938. The house was then used as a rehabilitation centre until 1963.
From 1963, the house was used mainly as a location for films and television, including and The Avengers. It was converted into Grim's Dyke Hotel in 1970 but continues to be used as a film location. The hotel retains 30 of the original 110 acres of land that Gilbert purchased with the house.
The house was designed in 1870 by Richard Norman Shaw for the Victorian era painter Frederick Goodall, who had purchased 110 acres (0.45 km2) of land at Harrow Weald in 1856, but he did not begin to build until a lease on the property expired. Shaw's design for the house included aspects of Gothic revivalism, added to a late-Elizabethan style, which included high red-tiled gables, tall clustered chimneys and leaded lights. To the north of the house, Shaw built a small lodge, a walled garden and various outhouses and a stable block, later converted into garages by W. S. Gilbert for his collection of motorcars. Over the dyke (now a duck pond) Shaw built two stone bridges, which incorporated flint from the ruined church at Stanmore. Construction on the house was completed in 1872. Goodall's ground-floor studio was built on a north-south axis in order to catch the light. Goodall sold the property in 1880 to Robert Herriot of Hambros Bank, who added a billiard room in 1883.Windsor Castle is visible from the house.