I have to agree with Murdoch, we have turned up to an old 3036 board often with no gas or water bond, undersized tails, undersized main earth conductor, and often connections not great. We have replaced the board with a C/U with RCDs, sorted all the other issues out and improved its safety. But some of the lights don't have a cpc, so we've highlighted this verbally to the customer, also in writing and put a warning sign on the C/U regards the danger etc.
The likelyhood of this ever ending up in court is very very very slim, but if it did I am confident that I left the customer's installation far safer than how I found it and I have clearly highlighted the issue with the light circuit having no cpc and I can't physically do anymore. The lighting circuit was there before I arrived, I didn't cause the lack of cpc problem n the lights, but I have definitely improved the safety of the customer's installation.
When I put my car in for a service and the mechanic tells me my brakes are dangerous and I refuse to pay him to fix them, is he then responsible if I have an accident due to my brakes failing. Of course he's not responsible, he can't force me to pay him to fix my brakes just I can't force the customer to pay to have their light circuit sorted.