In article ,
Grunff writes:
Andrew Gabriel wrote:

If your lighting circuit
isn't earthed, then you will need to take the lamp back to
B&Q and choose a double insulated one which doesn't need
earthing, and also note that you need to get your lighting
circuit rewired at some time (or rewire it first).

Can I ask why? This may be being naive, but if all your light fittings +
switches are double insulated, then is there anything inherently wrong
with a non-earthed lighting circuit?

It's going to be an old installation. It is a requirement that a
CPC (earth) is carried in all wiring for some considerable time.

--
Andrew Gabriel