Ah yes. Maybe it wasn't in use for very long? I must say that there does seem to be a drainage ditch taking the water around the edge of the structure.
There are so many of these hut circles on this hill side and at the base of Moel Faban that seem to have been placed in very damp areas. And not far away at Corbri farm there are 3 huts that are practically submerged. One wonders about the logic.
The hut itself is levelled out almost like it's on a slight platform or foundation. Further down is a mound of stones among the rushes. I couldn't quite figure it out as the rushes are long. It definately would warrant further investigation.
It was hard to tell as the rushes are so long here. At the other site I could actually find burnt stones in the mound. I could actually rub the burnt sooty stuff off the stones. (which blew me away really to think I was the first person to pick up those stones in how ever long) I couldn't really tell if there were any burnt ones here. I'd have to get right down among the rushes. Although I could see a mound it was quite low down. I had a bit of a fear of wriggly things among the rushes so didn't want to venture too far in.
(sorry this has turned into a small essay)