There is a good IET paper on this, and the myths clearly even if in 1900 we were allowed open knife switches, we can't use them now.
But as to using the regulations valid at the time, pre 1966 we had "Lighting fittings using filament lamps installed" and since we no longer have filament lamps, the regulation allowing no earth to lighting no longer applies, and also the same regulation refereed to "that they cannot readily be touched and are out of reach of earthed metal." so it was never applicable to wall lights.
There seems to be two items which present a problem, one is the earthing in bathrooms, it is far too easy for plastic pipes to result in loss of earth, and also sockets likely to be used outside, both seem to call for the use of 30 mA RCD protection.
So the RCD seems to be the biggest question today. Be it type A or AC, or if required, or if bi or omni direction.
Personally unless a TT installation the RCD is secondary protection, so not too worried, but it is a case of watch my back, so if you say it does not exist, wrong type etc, and either no code or code C3 you have raised the issue, I can't see a court taking you to task for wrong code, but they may for saying nothing.
But the IET myths busting was an eye opening for me, I have even seen code 2 on type of RCD fitted never mind missed out completely.