Yes, 1930s-40s most likely. Slip conduit didn't specifically pre-date threaded, it was just cheaper and quicker to install although less secure and effective for continuity. It's not likely to be late into the 1940s because changes in the ESR and wiring regs made way for SP fusing instead of the DP in those two boards.
The small board right is MEM, with Kantark Minor 15A fuses. The left one I am not sure about, is it Prento?