On the north-east side of the Brookmans Park Transmitting Station, hidden deep in the hedgerow, is a fine example of a spigot mortar emplacement. This is where soldiers, possibly Local Defence Volunteers (later known as the Home Guard), would attach their guns and patrol. Nothing special about the find other than it is not mentioned in any of the records in the Defence of Britain survey, compiled for the Council for British Archaeology. The survey mentions one spigot mortar emplacement to the south of the Transmitting Station, but missed this one.

Clearly the Brookmans Park Transmitting Station was worth defending during the war years as author Lilian Caras makes clear in her history of the transmitting station.
"When France was invaded in June 1940, there was a need to increase the power of the existing European Service and to overcome jamming from Europe. Consequently, a powerful 140 kilowatt transmitter was installed at Brookmans Park in an extension to the original building, which came into service on 2 March 1941. The station was of strategic importance to the war effort. To reflect this, the building was painted in camouflage paint and the windows bricked up or had metal shutters placed over them. Soldiers were camped in the driveway to guard the station. Although the original targets are unknown unexploded bombs fell in Georges Wood Road and Moffats Lane, Brookmans Park in November 1940, missing the nearby transmitting station."