An obstruction was noted by the UKHO in the intertidal zone at the north end of Margam Sands in June 1981 from aerial photographs.
This seems to relate to NPRN 409374 on the basis of their respective recorded locations.
Sources include:
UKHO ID 12523: Contains public sector information, licensed under the Open Government Licence v3.0, from UK Hydrographic Office.
J. Whitewright, RCAHMW, December 2023.