Hi Kammer, Also bought books whilst in Wales; and found this gem of an article in Pembrokeshire Coast National Park . Its the archaeology chapter written by W.F.Grimes, (Grimes goes with Grinsell down here in Somerset, ask Rhiannon) so will extract some relevant quotes for Pembrokeshire on stones;

"Standing stones; meini hirion; A recent systematic list, eliminating cattle-rubbing stones and the like give over 70 for Pembs., distribution mainly to the north of the county.
He lists the Parc y Meirw the alignment of 8 stones in a road bank, on this site, 140 foot long.
Pairs of stones are fairly frequent, and must have some special significance, particularly since the stones commonly conform with a regular pattern one being slight and tapering whilst the other is more massive (as at Avebury) e,g, are Cerrig Meibon Arthur(118310) , the Waun Lwyd stones (157313), Upper Lodge Stones (861142).
The dates and purposes of single standing stones are no doubt various ( I always think of them as bronze age, but their presence is often near earlier sites).
In other regions the frequent associations of standing stones with tracks suggest they are waymarkers. Others have been found to have burials at their feet, ( but which came first, the burial or the stone is never clear - was the stone put up for a special person, or was the body laid at the feet of the stone because it was an idol or cult object)..
Apparently there had been one stone excavated at (this article must have been written 30/40 years ago) at St.Nicholas, produced evidence of elaborate ritual practices.

He goes on to give other examples of impressive stones to be found, which I have'nt
time to type saying that he probably thought that standing stones went back to neolithic but marjority bronze age, some have a relationship with round barrows.
Mentions also The Flemings Way,( think The Ridgway) coming down from the Prescelli mountains to the Rivers Cleddau, the maybe trackway for the transportation of the bluestones..

Moss x