Can anyone identify this old wiring in my walls?
Partial answer: the larger cable is Belden 8290 shielded twin lead TV antenna cable, which was introduced the 1960s and so is probably original to the house.
It's been literally years since I posted this question so in all likelihood nobody will happen upon this, but while working in my attic today I uncovered an old UHF/VHF antenna that was laying on the rafters and buried by the blown cellulose insulation. After digging it out a bit I immediately recognized the wire it was connected to as my mystery large wire and could finally get a good look at it.
There was no sign of the smaller wire in the attic so what that was used for remains anybody's guess.