This morning I very nearly stood on Trip Hazard as I was getting him breakfast. He probably does not understand that 95kg of human could cause a partial and irreversible 3d to 2d phase transition. He would get squashed and I would fall.
I checked online and apparently it is not completely unusual for cats to go “walkies”. Sometimes this is due to separation anxiety, other times dominance or simple curiosity.
For a stray cat he is pretty friendly and keeps trying to get in the house.
He has not got an ear tattoo. But he might have a chip.
In France the wiring, certainly in the past, can go diagonal across walls, so a while back I bought this detector for studs, metal and current. Better to check…

I started thinking laterally.
A cat microchip must have some form of radio frequency coil in copper, probably.
So, I have just run this detector over Trip Hazard’s back. It showed a positive signal. But I need to get him onto the lawn to rule out any false positives.
If it is the case, we can get the chip read at the local vets.