I think I tried to visit this one last week Carl. Quite close to Lamborough Banks long barrow and just by Saltway Barn. Could just about make out a mound, more like a round barrow than a long barrow, it seemed to be in the centre of a plantation of saplings and surrounded by a stone wall.
Timothy Darvill in his book 'Prehistoric Gloucestershire' says the that, when excavated, it was discovered to be a beehive chamber tomb. I asked a knowledgeable contact (who would probably prefer not to be named) if they knew any more on the subject.
This was their reply:
"The Cotswold beehive tombs are sometimes known as rotunda tombs quite distinctive and not really related to the later and more commonly known by the term beehive tombs of the Myceneans . The Cotswold (and Welsh) rotunda graves are found under long barrows e.g. Notgrove, Ablington, Tinkinswood (possible) and believed to the earliest funerary monuments for the area. Basically they are a slab lined cist covered with a mound. Can't think of anything that is actually just about them, they tend to get mentioned in passing as Darvill did and some don't consider them to be worthy of a separate typology."