Boundary Wall, Piers and Southern Gate

The boundary wall, piers, and southern gate are located on Heath Street and date from the early 18th century, with later alterations. Constructed from pink-red bricks in Flemish bond, the wall features stone copings on the gate piers. It extends approximately 60 meters in length and stands about 2 meters high. A later 19th-century section of pink-yellow brick is found between the middle and southern gate piers, alongside a 70-meter stretch of yellow brick in Dutch bond that begins at the second of two distinctive insets.

There are three gate piers integrated into the wall, with the two southernmost featuring wrought-iron overthrows. A spiked iron bracket is located at the bend of the first inset, and a wrought-iron gate from the 18th century is set within the southernmost gate piers. The coping along the entire length of the wall has been renewed.

Historically, this wall was once part of the Upper Flask Tavern, which served as a summer meeting place for the Kit-Kat Club and is mentioned in Richardson's 'Clarissa' from 1748. The tavern was converted for domestic use in the late 18th century and renamed Upper Heath, but it was demolished in 1922 when Queen Mary's Maternity Home was constructed. The wall is depicted in several topographical prints of the former Upper Flask, showing that the middle section of pink-yellow bricks replaced a dwarf wall that previously allowed views towards Harrow. Anna Maxwell's book 'Hampstead' from around 1910 noted the impressive sight of the strong, high garden wall at the top of Heath Street, surrounded by ancient towering trees.