I've just heard from Sue Dutton, the archivist for Bishop Strachan School, and she has no information about why a pair of chimps appears on the school building.
" We also have a dragon and a lion, but I have never seen any documentation that explains these decorative choices," she wrote in an e-mail. "The oldest wing of the current school building was built in 1913-1915. Although the BSS Prospectus for the 1915-1916 school year goes to great lengths to describe the style of the new building, Collegiate Gothic, and many modern features such as hot-water heating and sound-proof music rooms, it does not mention these sculptures. I believe it can be assumed they were simply added as whimsical decorations that the girls attending the school would enjoy."
I've read similar articles in architectural journal that frustratingly, elaborate the innards of buildings but either never mention the outside (beyond a simple description, such as "Collegiate Gothic") or refer only vaguely to sculptural details, but not in detail.
But I am convinced that architects didn't and don't stick any old animals or bearded figures on their buildings for the hell of it. There's a reason, although it may have been lost.
South High School in Denver has an extensive sculptural programme - and the background information explaining the architects' choices is contained in the school's yearbook. Stay tuned for a forthcoming post featuring pictures from that school.