I'm still struggling to see how this means the meter is registering usage when the 'light' switch is on.
We've got incoming tails, no neutral connected to the meter. Then L out N out of the meter, L goes to main switch, N is switched and goes to main switch via earth bar, which means the circuit must always be using earth as the return since there's no other neutral in the circuit? So when the switch is off, there is basically no actual neutral in the circuit, not in or out of the meter, and there will be a line into the CU and only an earth out, am i getting that right?
Basically would this not function exactly the same without the switched neutral at all?
I've done a sketch of what it looks like to me.
Key:
Mtr - Meter
SH - Service Head
SW - Switch
E - Earth bar
MS - Main switch