Security light on FCU, is this really necessary?

[IfInDoubtDIY]

So it seems. I asked a simple question and am rather baffled by what is being thrown at me!

Certainly not necessary. You would be replacing a DP switch+fuse with a DP switch without a fuse, and the fuse is doing no harm - so it would just be a waste of time, effort and money.

You seem to have convincingly established that the FCU is fed from the lighting circuit. Had that not been the case (i.e. if it had been fed from the sockets/power circuit) then that would have been a reason NOT to replace the FCU with a switch, since the fuse in the FCU would when have been serving a desirable function.

Thanks John. You and @SUNRAY have suitably convinced me - I’m not keen on doing unnecessary electrical work.