This is not listed in the SMR. As I ascended south towards the summit of Broughills Hill from the barrow in Johnstown, along the boundary line between Johnstown and Kiernans Hill and in turn Broughills Hill, I spied a large, rocky outcrop. Though I was making for the summit in driving wind and rain, I couldn't resist investigating. The outcrop is made of huge earthfast granite boulders, but below it to the east is a seemingly man-made platform containing this intriguing monument.
I can't make out what it is, so I've listed it here as a hut site/habitation site, though i suspect that it may be a burial/chambered cairn, ruined and lost to history, until now. There are lots of lumps and bumps in the small, 8 metre diameter area, some of which may be a chamber, or may be the hearth of an old hut site. In the north-west quadrant there is erosion leaving packed, cairn-like stone visible. The whole mound is about half a metre tall, rising to a metre in places.
A mystery, leading me to reckon that this ridge, leading down from Broughills Hill, has not been properly surveyed.