Hamish, that's very interesting what you discovered at Ogbourne St Andrew. It alls seems very tantalising.
As a result of looking at your posts I was looking on the map and there's another barrow apparently directly opposite on the other side of the Og valley too. Dunno if that's relevant. It just seems in a Good Spot compared to the one at the church (looking on the map at least).
Looks nice and shady on these hot days too.