Update.
Following the description of the boulder surface (from a visual inspection) by Prof Peter Kokelaar we have now updated our Interim Report:
https://www.researchgate.net/publication/358426131_A_newly_discovered_giant_erratic_at_Limeslade_Gower_Peninsula_Interim_Report
Contrary to rumours, we are blithely unconcerned about where the boulder has come from. It is not spotted dolerite, so it has not come from a spotted dolerite tor on Preseli. It might have come from one of the igneous intrusions on the North Pembrokeshire coast. We shall see. The sample is currently being analysed, and when the work is complete it will be published by a "competent geologist".
Something is not right. This message is just to keep things from messing up down the road