Royal Observer Corps (ROC) monitoring post

The Royal Observer Corps (ROC) monitoring post is a Grade II listed structure, built between 1958 and 1961 to a standard design from 1956 by the Air Ministry Works Department.

Constructed from reinforced concrete and covered with compacted earth, the post is situated on the south-west boundary of Dunsfold airfield. It appears as a rectangular, flat-topped mound covered in vegetation, featuring a raised entrance shaft at one end and a smaller raised air vent at the other. The concrete entrance shaft includes a counterweighted steel hatch, metal ventilation louvres, and a fitting for the Ground Zero Indicator, which is a device used to detect the direction and altitude of nuclear explosions. A stepped brick mounting block is located next to the shaft.

Inside, the vertical entrance shaft is 4.6 meters deep and 0.6 meters square, equipped with a steel access ladder. At the bottom of the shaft is a drainage sump with a metal grill, which retains its wall-mounted rotary hand pump. The shaft leads through two timber doors into a small closet for a chemical toilet and into the monitoring room, which measures 4.6 meters by 2.3 meters. The walls and ceiling of the monitoring room are clad with textured polystyrene tiles, likely added later for insulation. The room features rubberized flooring, two crude fitted wooden tables, a cupboard, and some fitted shelves along one wall. The walls also have metal and plastic trunking, and at the far end, there is a metal ventilation flue shutter. The room retains fittings for a fixed survey meter probe, which recorded external gamma radiation, and a bomb power indicator, which measured the size of a nuclear explosion.