The site is actually in <i>Cashel</i> townland and you found the right thing.
Yes, it's a court tomb and it's pretty darned ruined innit :-)
Thats great FW thanks for that, it had to be a court tomb but as I said in my fieldnotes I am amazed by the uniformity of everything . A sign written on a boulder on the opposite sde of the road read Castlenageeha and this matched my OS map.