No dwelling-house in London has so fine an entrance as Grosvenor House, the Duke of Westminster's town residence, which lies back from the south side of Upper Grosvenor Street. The house itself was built for the Duke of Gloucester, son of George II; but the entrance, as well as the western wing, both designed by T. Cundy, are of much later date, the latter being completed only in 1842. It consists of an open scene screen of classic pillars, connecting the arches for entrance to and exit from the house, the whole elaborately decorated with armorial bearings and other carvings. The gates are fine examples of metal work. In Grosvenor House is hung the Duke's almost priceless collection of pictures. Meetings are occasionally held here in aid of philanthropic institutions in which his Grace is interested.
source: The Queen's London : a Pictorial and Descriptive Record of the Streets, Buildings, Parks and Scenery of the Great Metropolis, 1896