"2 core lighting cable-no cpc

[Albert]

In the grand scheme of things, sorting a broken ring is a lot more important than missing earth on lighting. Particularly, as you said, if someone has already organised some sort of fix to provide an earth at the lighting points. Presuming it really is connected.

Yes I agree, but here is where part P is involved, rectifying/changing a damaged circuit, that has to be connected to the CU is a notifiable job, so I can't do the lights in any case, concerning the ring, I can try to identify the socket where the ring is broken, otherwise again rewiring is notifiable. I don't know how important is the fact that the downstairs sockets are not protected by a RCD, I am sure that the occupier uses a hoover to clean his car... (in my house all my sockets are protected by RCBO's)