The Playhouse, a Grade II* listed building, was originally built as an ancillary building to the former Victorian water pumping station. The engine house and the playhouse complex serve as a climbing centre since 1994 after being largely redundant.

London Stone Conservation completed the external repairs to the north and east elevations. The works included stucco, brick and stone repairs to the chimney stacks, parapets, cornices, pediments, walls as well as lead flashing repairs.

The Engine House was built for the New River Company between 1852-1856 by William Chadwell Mylne, acting Surveyor. Built with London stock brick, the playhouse reflects the same architectural style as the main engine house. The building has crow stepped gables and buttressed walls with stone and stucco details.