Quoted from Apollo

It is actually somebody's garden, on the Hammy Road, but on the roadside.

I actually attribute the black corner to industrial era soot that wasn't cleaned off by a shoddy stonecleaning job on the sandstone - I think there are quite a few similar examples to be found.

Can you home in on the York Terrace you have in mind?

It seems to ring a bell, but I can't place it on any online maps, which don't seem to find any in Glasgow! (Assuming I'm not confusing the name with something similar of course).

This one  

You're just trying to make me look at old maps.

Still can't come up with that name though

Yes, haven't actually been there for ages though, and think the Mazda suggests a recent shot as I only spotted it once when I had to pass the spot.

Afraid the "York Terrace" is a new one to me here, so I'll have to ferret the name away, and keep it in mind to see if an ancient reference to its origin pops up anywhere. Perhaps connected with the architect, owner, or builder?

Are you familiar with the "Honeymoon flats" further along the road to the west?

(While having a look at this spot on Google Maps, it is clear that the individuals placing interesting spots on the mapping service are deserving of being placed up against a wall and shot. Just have a look at some of the placements made nearby - someone couldn't even manage to get Eastbank School tolerably close, and as for the subject of some of the other placements, they really are waste of space. I don't think any of them need apply for a job involving benchmarks!)

I thought I'd wander along to the rest of the road where I spotted the Hogmany party benchmark above, and see if there actually was further evidence.

There was only one genuine crow's foot benchmark carved into one of the "big house" walls, or its gatepost to be accurate, while the rest were just GPO markers.

I included these since I was there anyway, and one seems to have been forgotten, and has no markings!

The other two show how the weight of responsibility for the cables they protect can weigh them down with worry, and they sink under it

There are a few more, they're hardly rare or unique, and many seem to have been laid into by someone with a hammer to destroy the markings, but unless one turns up with a number stamped in the lead blank, not really worth "collecting"

I wandered along the London Road for a bit, but the walls behind the Victorian era houses have largely been destroyed by modern works and the road, and all I found was another GPO marker, fairly chewed up and lost in the vegetation that grows along this particular road, although much of this was chainsawed and cleared a little while ago.