This is the next stage in the new lounge wall lights saga.
I've now checked the lighting wiring, and most is not earthed (checked for continuity with a known earthed 13-amp socket). But there is - usually - an earth wire in the old cable. This summarises the lighting wiring:
Light 1. This has the cabling at a strange angle. The connected wires are red and blue; there is a white wire but this is not connected. There is a bare earth wire, not connected to earth by continuity test.
Light 2. This Is connected via a spur from a 2-amp socket. It failed the earth continuity test. I opened the 2-amp socket and found it was also wired up with red and blue wires, and an unconnected white wire. There was a bare earth wire (although green/yellow sleeved) connected to the socket earth, and the spur cable earth wire, but this green/yellow sleeved earth also had no continuity when tested.
Light 3 Is not on the same circuit as the other two, and is not operated by the wall switch. It has red and black wiring, and a bare earth wire. This is connected to earth as it passed the continuity test.
The wall switch has red and white connected wiring, and a blue unconnected wire. There is no earth wire at all. The switch is plastic, but fitted to a metal pattress in the wall. (NB the cable is grey PVC, all cable to the wall lights is white PVC.)
So the questions:
If it passes insulation tests, could the current wiring to the lights be used if the earth was made functional?
Can it be made functional by simply connecting it to a known good earth point?
As the switch is not earthed and has a metal pattress, does it need new cabling and the pattress connected to earth?
If I have a new central ceiling light connected up (using cable which complies with the current regs), would an electrician be allowed to connect it to the old cabling (assuming that cabling is safe!)?