As I understand it from the plan, what you are looking at is the man way and the separate hopper.
The original way down, pre SRT was via the calcited ladders but I think over the years this way down has become a little challenging.
So the hopperway(timbers long gone), is used a the preferred safer way.
Not sure about hopperway, unless that's beyond Bog Shaft...
I was looking at 2 calcited manways (with ladders and one with ropes as well) down from the sub level below Smallcleugh Horse that you reach either by the ladderway down from SC or by the sump in the bottom of the stope. The one without ropes is on the opposite side to the one with IIRC.
Don't look so embarrassed, it's a family trait...