Terrace wall, with garden steps and grotto, between the middle and lower terraces to the rear of York House

The terrace wall, garden steps, and vaulted chamber located between the middle and lower terraces at the rear of York House date back to the late 17th century, with some later alterations.

The terrace wall supports the broad, level middle terrace to the south of York House. This terrace originally extended westward to the western wall of the York House garden, but that section was rebuilt in 2012.

The vaulted chamber, made of 17th-century brick, is situated just east of the wall leading to the Cloisters' garden. Its rear wall does not connect to the side walls or the vault, suggesting that the vault may extend further beneath the middle terrace lawn. The front wall, constructed from thicker 18th-century brick, features a round arched window opening and signs of a former doorway. Much of the original early brickwork of the terrace wall behind York House is obscured by later 19th-century brickwork, particularly around the two projecting platforms beside the main stairs.

The stairs, designed similarly to those located 15 meters to the north, align with the central axis of York House. They consist of eight steps flanked by low chamfered parapets leading down to a landing, which has an additional eight steps. The nosings of the steps are moulded.