Don't ask

This is a picture of the inside of a light switch at my mother-in-law's. It is a twin gang device and each switch being dual pole. One switch is used with another switch for the hall and the second is used on its own for an external light. It's not been working well and it was in a mess. The French use a crazy system where each manufacturer uses their own proprietary fit back box and front plate and even over time they change so fall out of compatibility within the same manufacturer.

It made no sense, and no matter how many times I tried to make it work it wasn't having any of it. The electrician said rude words and replaced this monstrosity with a new assembly the following weak, but has the advantage of circuit testers to figure out what bat s**t wiring had been installed and was able to make it work.

This is a back blip, and just before Xmas the external light was removed to make way for external insulation being installed this spring, and because the wires were lost, the second switch on here is now connected to nothing!

French domestic electrical wiring is a joke at the best of times, even when done by a competent professional, however most people aren't competent and they do really strange things...