Looking at your photo there seem to be two stones in the picture. Are they stones? If so are there any more? i.e. is the there the possibility of a tangential row? Could be important. I doubt someone would have made the enclosure to butt up to the row. It is more likely that they are contemporary or the row came later (if it is one).

35m is not all that small for a henge if you broaden your scope. A few Irish ones are of around this size.

It could be a ring barrow.

It's nice to have another "discovery" this week. I stumbled across this last Sunday - http://www.themodernantiquarian.com/site/6807 - (also not easy to photograph). It seems to be classed as a hut circle (or is totally unrecorded), but I reckon it's the remains of an axial, embanked stone circle similar to Boleycarrigeen 1km to the west (which would be visible from here if it weren't for a pine plantation surrounding Boleycarrigeen!)