I'm not Welsh at all Dave, gets a great view on mine- make sure it's Microsoft, not Google Maps or Google Earth... the fort is the squarish feature with a farmhouse in one corner. Follow the broad slope to the east north towards the river, lots of features there of unknown date, but in the field just inland there are a number of circular features that might be British huts. There should have been a road crossing somewhere nearby- any suggestions?

I find it hard enough to spell FORWARDS in Welsh, let alone backwards... SNALWIBMA SNALWIBMA SNALWIBMA SNALWIBMA SNALWIBMA.