gregmcc:

 

It is quite common in older houses pre early 80's where lighting circuits were 2 core only and no earth as they supplied a batten holder light fitting, it was also very common for the live to go to the light fitting and then a 2 core run to a light switch (with no neutral at the switch).

 

As far as i'm aware there has never been any requirement for an earth to be present at a light switch, there is a current requirement for an earth to be present at each light fitting (needed or not).

 

Yep loop at light or Loop at switch.

I always preferred the loop at switch, fewer issues with wiring getting damaged due to the heat from incandescent lamps