A ruined rectangular brick-built military blockhouse, assigned number 5 of ten total protecting the wireless site, measuring 11m long by 9m wide and 2m high. A stone extension with brick quoins   was built against the eastern elevation in 1923, when the building was repurposed as a workshop and storage area for the building of an antenna extension array. A firing ring of internally-fluted shooting holes with slate upper faces runs at head height around the building, mostly blocked-up with brick fragments and mortar different in composition to the building’s brickwork, most likely to provide a weatherproof interior during repurposing in 1923. Sockets for the timber of a second floor, almost certainly used as rudimentary living/sleeping quarters during WW1 are evident in the internal brickwork and, as for the other blockhouses a window was installed, here at the southern gable. A vertically-slotted metal ventilation grille survives at ground level to the east of the doorway within the southern elevation.

Source: Rowlands, J., Marconi's Carnarvon Station 1912-1939: a journey into early commercial wireless in north Wales' Second Edition, 2023.

RCAHMW, 2023.