Phil, here is a photo of that part of Abbey Street in 1907. The Black Horse is just to the left of the lamp post in the middle distance.. Going away from the town centre there are then your three buildings. The fourth one from the Warner Street corner appears to have a sign board over but I can't make it out. It's on what looks like a projecting porch.
I post this really just out of interest, not because it throws any light on our quest for a pub.
http://lanternimages.lancashire.gov....21&r=2&t=4&x=1