The crescent of houses near the cache are built on the old site of the manor house of Farmhill park which was built in 1784 by Richard Cooke a Rodborough clothier who unfortunately died before it was completed. It was sold in 1833 to Henry Wyatt who built the arch as a memorial to the abolition of slavery at the entrance to the lower drive he constructed. The arch and a small section of curved wall is all that remains after the house was demolished and the estate built on.
This is a high muggle area with dog walkers so you need to be stealthy.