The Box on Cowcaddens Street at its junction with Port Dundas Road, opposite the Buchanan Street Railway Station - E11.

(Note: the only reason it's not being tagged as the Buchanan Street Station Box is to avoid confusion with the Buchanan Street Box - A19.)

From some time in the 1950s --



A blowup --



From the early to mid 1960s --



From circa 1966 --



Two screen caps from 03 September 1966 --





From some time in the 1970s, after the Box had been removed, to better show the area the Box was located --



The OS Maps showing this Box:

From the 1951-1952 map (centre of map, marked "PCB" just above the "TCBs") --



From the 1966 map (partial coverage) --

Couple more pics of this box here.