Visited 14.8.2009 on a cloudy walk up from Blaenavon. The site is both better than expected and a bit of a disappointment - better than expected as the position is superb, with excellent views north over the Black Mountains, to nearby Blorenge and the Sugar Loaf; a bit of a disappointment as the 1.7m stone in Coflein turns out to be rather smaller - less than a metre in height.
It has the inscribed M and B, and there is another smaller, fallen stone a little distance to the north, nearer to the edge of Blaen Pig. Definitely worth a visit, depsite the shrinking size of the stone.
"This is an ancient standing stone erected (according to tradition) in early British times to commemorate a battle which was fought here between two kings or chiefs, one of whom was named Ifor.
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About 1km to the south east of Carreg Maen Taro is the site of two burial cairns called Careg-Croes-Ifor (nprn 405021), presumably the same Ifor mentioned above, and Pen-ffordd-goch (the head of the red road) (nprn 404999), 1.5km to the south east, is said to take its name from a battle waged there; there thus seems to be a vague tradition of a battle fought somewhere in the area.
Chunky standing stone 1.7m high on the boundary of Breconshire and Monmouthshire. It has the letters "B" and "M" inscribed, reflecting the two counties.