I'm willing to believe that these rectangular holes were made by an iron chisel after looking at these pictures
http://www.themodernantiquarian.com/image.php?image_id=19711
so Iron Age gateposts --- maybe.

The tradition of erecting stones is still alive - but only just ...

I made a lovely pair of standing stones last week (just little ones). No photographs. I also took a little one down and hid it where the stonecrusher man can't find it over the winter. There's a small chunky broken stone circle, two ballauns - one tiny one huge, and either the capstone of a cromlech or the missing fourth stone of a four-poster - in his way that I can't do anything about. Because the White Sultan's man built a road in the SSSI and put two enormous cairns through the crusher then the local landowners think it's open season on the antiquities - which are on the SMR but not Ancient Monuments. Lovely wall. It's a double circle at Kirkhaugh, with a diameter of about 70 - 75 m. Small henge is like a chevron across the middle 7m. wide and about 33m long. Strange construction - closed flat faces with a rubble filling. The circle can only be made out from the railway track - on the ground it's just a painful jumble of stones.