History of Wigan   (Help with ancient and recent history.)

"This is possibly the pub I am confusing with the one at the bottom of Coppull Lane (or maybe I have become confused over the years on the original narrative). Yes, it looks like the position where Mabbs Cross School was eventually built."

I believe, The Green Man pub which can be seen via the link "mrs m" kindly posted was not where you think it was (where Mabs Cross School now is).
I believe, this pub was on the opposite side of the road (Standishgate/Wigan Lane).
The pub (a 3-storey high, brick building) is similar to the building which was on that side of the road when I was a kid and which, I am sure of, still stands; this building was empty and was connected to an empty old house (also, 3-storey high) which had obviously been, at one time, a beautiful home of a family of status. Later, this large, beautiful house was owned by Jimmy Collins. I think that it is number 136 Standishgate.
I strongly feel, the part of the building (on the photograph, to the left) where there are four steps up to the door and three windows can be seen is the same building which is still standing. Therefore, it looks as though the part from the four steps to the far end of the building (to the right and past where a man is standing in the road) was demolished.
I believe, The Green Man pub (shown via the photograph posted) stood on the land where the flats now stand and which are opposite Mabs Cross School.
I hope this is of some help.