Can you imagine with today's cost of real estate how much all of that space would cost now?
There's a substantial amount of empty space in a lot of C.O. buildings now. Look inside even something as recent as a 1970s building which originally housed a TXE2 *
and now that they're just housing a digital remote concentrator unit there's a lot of empty space in the main apparatus room. *
TXE2 = T
lectronic No. 2, something like the American #1 ESS in overall design.
BTW, the battery casings appear to be wood with dovetailed corners.
They are! Click here
for a page which describes some of the different cell construction methods.
What is the 'Pilot' battery in pic 4 Paul?
Most likely a separate battery supply for the pilot indicators used to signal various calling and alarm conditions in the building. For example, on night service the manual board might have been switched so that incoming calls not only illuminate the calling lamp over the jack itself, but also sound a buzzer and/or illuminate a master pilot lamp at the end of the suite to draw attention.
This battery bank would have been an older installation even in 1950. Some of the earlier manual exchanges used 22 or 40V, and quite a number would have still been in service at that time. 50V became the norm in later years, and of course for automatic switching.