In message , Philip
writes
Thanks for the replies. I have some follow-up questions.

One poster said to tie my earthing requirements back into the main
earthing system.

The cabling we are talking about here is all in the loft of the house
and I do not recall seeing any earthing cabling up in the loft at all.

Well you wouldn't normally see any separate earth conductors.

The lighting circuits do not have any earth wires and there are no
power sockets in the loft. Only a single lighting circuit.

So you mean the cable that supplies the wall light points has an earth
conductor, but the circuit that it connects to presumably predates this
and does not have one?

In that case you need to add one back to the consumer unit. I don't know
if connecting to the earth on another circuit is allowable, but I
certainly wouldn't want to do it. While you could add a separate earth
cable back to it as suggested, I would look into rewiring the lighting
circuit with T&E (you could do this in bits as you decorate)

Should I look further for an earting system up there.

I would certainly want to check over the whole system

This is a
1930's house with a wiring system from that era, although most cables
are of the newer (white PVC) type I suspect the wiring layout design
is of the 1930 era.

We have a '30's semi, partly rewired in the 1960's. If our experience is
anything to go by you will end up rewiring the lot eventually anyway.
Lighting circuits won't have an earth, there won't be enough sockets -
don't assume a sensible ring main, ours was a total hotpotch of a a ring
but most of the sockets were pond various spurs all over the place.

I would want to check that there is no of the original probably 1930's
rubber cable - if so you want to get rid of it ASAP (look carefully,
some of our switches had PVC cable that connected to the original rubber
cables buried in the wall behind the switch)
--
Chris French, Leeds