I mentioned in an earlier post that the renovated buses (of the type in the photo) were principally rush hour and short working. This bus is either on the full route, just joining or leaving it as short workings usually mentioned district names.
The only other structure in Icknield Street with any resemblance to Spring Hill library is, in fact, Icknield Street school. (now part used as a religious place).
All photo of the school I have seen show only a three quarter view and the same view in every case. I have not seen a photo of the other side to that usually found on the web.
The late Robert F. Mack, who is credited with the photo in post 6 and probably was the photographer in the original post (taken probably from the book at some point), took photographs of many buses and trams in Glasgow, he also was active with his camera in Yorkshire; there are a couple or so books by him.
Many of the photos in the book Inner Circle 8 are credited to him.
He seems to have been around at the end of the 1950's and later in the later part of the 60's.
I get the impression that whilst he was the photographer the descriptions of each photo in the book are by those who wrote the book. Maybe they fell into the same trap most of us have on this thread!
