Penlan embanked circle?

The Stones of Stonehenge team will be doing some non-invasive geophysics at the Penlan (or Troedyrhiw) stone pair during the coming fortnight, in the hope that the stones might be the last remnants of a stone circle.   Hmmm.....   Anyway,  I offer this as something that might be worth a look.  I think I see (on the Bing satellite image) the traces of an embanked circle about 200m due east of the standing stone pair, in rough ground on the other side of the road leading to Carnedd Meibion Owen.  Grid ref SN09226 35713.  A bank has been cut across it.

If there is a circle there, its diameter is about 50m.  I haven't been able to do a comprehensive search, but I'm not aware of anything in the Coflein or other records.

In my view it's worth taking a look.......

The Possible circular structure is slap in the centre of this image.

PS  

Thanks to Steve for pointing out the proximity of the assumed site of St Brynach's Well.  Very interesting!  I know people have been hoofing about over there, trying to find it..........

Here is the annotated record:

So -- "Above that range of rocks called Carnedd Meibion Owen, on the side of the mountain by the highway, and is compassed round with a curtilage of stone wall called Buarth Brynach ? Brynach's fold, the wall being of 6 feet thick?. In 1914 no traces of the stone wall existed."

That means there was a substantial fold or enclosure here, with a very thick bank or stone wall.  Was it at the marked position of the well or spring, or could it have been a little distance away?  In other words, could the original spring have been where the embanked circle is marked?  Investigations needed....