Don't usually get involved in this sort of thing, but a neighbour collared me on the way in from work.
Her kitchen ceiling light has been flickering recently and her husband had a 'look' at the switch. Now the ceiling light doesn't work. Might of course be nothing to do with him at all.
Light not on, no power to fitting at all. Bulbs OK, switch operates properly.
Two gang switch on the wall, one switch operates an under cabinet light which works fine. The other side should operate the ceiling light.
Inside the switch are three cables;
Cable A has the red to Common terminal, black to One Way terminal on the ceiling switch.
Cable B has the red to Common terminal on cabinet switch, black joined to black on Cable C.
Cable C has the red to One Way terminal on cabinet switch, black joined to black from Cable B.
Checking for continuity in the ceiling rose (only two wires) the black cable in the switch connects to the red in the rose, the joined neutrals in the switch connect to black wire in rose.
Having disconnected the switch I checked all the wires for power against the joined neutrals. Only the red from cable B was live.
If it's something simple or her husband has twiddled where he shouldn't I will sort it out for her, so any advice appreciated.