To add to your list, Burl mentions a possible stone avenue at Twinhoe, about a mile from the Stoney Littleton Barrow. Apparently the stones were incorporated in a farmhouse, theres a 1966 somerset report somewhere in the library, will check it out one day but I don't think it said much. Drove down there the other day (Twinhoe) its very small, farm settlements, upper and middle Twinhoe, I think it would have been the farm down by the brook; there's also a barrow on the other side. Notice in village "Please Drive Slowly free ranging children and animals...