Re: Seems fine to me
Lead sheathed. The conductor is probably Copper. The Copper conductor is rubber insulated, and then there will be waxed paper or cotton covering that with a Lead sheath on the outside. Quite a common wiring system in the first half of the 20th century in the UK, possibly into the 1950s.
I have a very interesting book that not only tells you how to maintain a "small gas engine", build a dolls' house, construct a chest of drawers, install a long-wire radio aerial and develop film, but also how to "install the electric light", with a discussion of the different types of supply available including accumulators - and how to recharge them - d.c. and a.c. systems with various frequencies and pressures.
It's a fascinating read.