I only ever visited N Ireland once during the "troubles" and on my way back to the airport I was driven through a "loyalist" area. The murals on the gable ends of houses were amazing in terms of artistry. I never saw the murals on the "republican" areas directly with my naked eye but from TV pictures they looked equally well done. I often wondered who these amazing artists were. It would have been a real education to have watched their murals' execution from start to finish.
Used to pass by an advertising billboard PAINTING business in a multiple story warehouse-like building next to Highway 101 in Oakland, California. San Francisco Chronicle profiled the place and painters in the 80s.
I wonder if they're still in business? I wonder if technology (like inkjet) has terminated them?