Cicero wrote:

[PVC]
It was certainly available in the early 1950s but I think it may have been
available as separate single cables rather than sheathed.

The transition period from TRS to PVC for twin and twin-and-earth cables
was quite long.

Someone[1] posted the following list of dates on the IET wiring regs
forum not too long ago:

quote
Try these approximate dates:

Lead sheathed cables: pre-1948.

Tough rubber (TRS): 1945-1962.

Capothene and Ashothene Sheathed Cables: 1952-1960.

PVC/PVC cables without cpc (lighting): 1955-1966.

Imperial cables PVC: 1955-1971.

2.5mm PVC/PVC with 1mm cpc: 1971-1981.

Black earth conductors: pre-1966.

Green protective sleeving: pre-1966.

Absence of main equipotential bonding conductors: pre-1966.

2.5mm main equipotential bonding conductors - small installations:
1971-1972.

6mm main equipotential bonding conductors - small installations: 1966-1983.

10mm main equipotential bonding conductors - small installations: post-1983.

Twin twisted flexible cords: pre-1977.

Fault voltage operated circuit breakers: pre-1981.

Accessories mounted on wooden blocks: pre-1966.

Non-13A socket-outlets pre-1955.

Double-pole fused switchgear on AC installations: pre-1955.

Others might may have other recollections. I appreciate that some
things were being used some time after the dates e.g. 15amp sockets.
/quote


[1] Original source he
http://www.theiet.org/forums/forum/m...nterthre ad=y
(edited for typography by the present author).

--
Andy