A small square concrete base for a ca. 30 foot tall steel lattice mast, part of an extensive support system for an elevated counterpoise for the 1923 long wave antenna extension array. It measures 1m square by 0.4m high, with embedded remnant steel lattice feet.
Source: Rowlands, J., Marconi's Carnarvon Station 1912-1939: a journey into early commercial wireless in north Wales, Second Edition, 2023. Dimensions by P.J. Schofield, OANorth, 27th June 2007.
RCAHMW, 2023.