Gazebo and Grotto Below in Back Garden of Number 20

The gazebo and grotto in the back garden of Number 20, formerly listed as the gazebo in the back garden of Number 18, dates from the early 18th century. The gazebo is constructed of finely-jointed red brick in Flemish bond, featuring decorative vertical strips of paler pink brick and ashlar dressings, with the roof not visible. It is square in plan and one storey high, with a chamfered plinth and rubbed-brick flat-arched openings on each side, flanked by similarly-arched narrow recessed panels, each topped with a brick cornice. The north and south sides have sash windows with glazing bars and exposed sash boxes, while the west and east sides feature double part-glazed doors with 4-pane overlights. The parapet has three panels on each face and a moulded stone cornice.

Inside, the gazebo has fielded panelling on the walls and reveals, a cornice, a corner fireplace, and panelled folding window shutters. The gazebo is built on a small mound that covers a brick cross-vaulted grotto below, which has round-arched entrances on the north and south sides. This structure was originally part of the grounds of the Wanstead Grove estate.