Royal Observer Corps monitoring post

In all but a very few instances, the posts were built to a standard design consisting of a 14 foot (4.3 m)-deep access shaft, a toilet/store and a monitoring room.

Of the two crews of four personnel engaged in staffing the post during this trial, the second group of four, two ROC and two Home Office Scientific Advisory Branch, were sealed inside with rations bedding and barracks equipment.

[1] The protection provided by the concrete roof and compacted earth mounded above the post was estimated to reduce any external nuclear radiation by a factor of 1,500:1.

Construction of the original 1,563 posts was overseen by the Air Ministry Works Department and the ROC and undertaken by local contractors.

Soil was compacted over the structure to form a mound leaving the access shaft, doubling as an airshaft, protruding above ground.

Approximately half of the posts built have been demolished, either on stand down by the ROC or by private owners in subsequent years.