Watch House Break Position Finding Station is located on the slop above Fort Bovisand. Built in 1894, the Position Finding Station (PFS) consists of six cells which are connected to each other by an underground tunnel. This tunnel, cut and cover, is concrete lined with lighting recesses. It is believed that this is probably a unique PFS with this feature. The tunnel systems is accessed through an entrance in the counterscarp, opposite to the scarp gallery. See plan.
The cells all remain, but the sloping iron and concrete roofs, covered in earth and grass, have now been removed. Some of the pedestals still remain in the pits. A blockhouse used to protect the entrance to the tunnel network, but this has now been demolished.
The PFS served the Batteries on Staddon Heights.
In 1911 the Position Finding Station, or part of it, was remodelled to function as a Night Director Station for the Officer Commanding Electric Lights (OCEL).
Just to the west of Watch House Break Position Finding Station is a small collection of three buildings, one of which is shown on the 1896 Map (TNA WO 78/2314) but not named. This position is dug into the hill side and gives access to the tunnel that leads through to a doorway that gives access to the Watch House Break Position Finding Station, see plan. There has been significant modifications during WW2 and possibly earlier. A pedestal still stand in one of the buildings. This has previously been identified as a possible PF location, or possibly Fire Command Post.