In article , chris French
writes

Yes, it would be worried about the insulation inside this cable which is
likely to be rubber - or rather I'd be worried about the insulation at
the ends of the cable where it terminates.

In our old house the cores were wrapped in waxed paper, not rubber,
inside the lead sheath. Joints were made by soldering the wires
together, insulating them with tape, and then wrapping a sheet of lead
around the joint and soldering it to the sheath of the wires entering
the joint. (for example, joints with three wires resulted in a
triangular lead "blob" soldered to the three incoming wires.) Quite a
work of art, but bloody frightening to still see used in this day and
age. And people used to run irons and things off the light sockets
using this wiring...

--
..sigmonster on vacation