Another thought I had, stimulated by Dickie's Odin wagon gate photograph.
I do not think we have recorded where these pack wall formers are found.
As some of you will know it was a stipulation, by the Grenwich Hospital that all the horse levels on Alston Moor had to be drystone lined.
I was told by an old miner that one family(presumably a large one), was responsible for all this arching.
My point is the iron formers used to make the arching are often abandoned or later stuck in walls by VM miners, we see them but do note where they are.