I hadn't realized the large silver notice was just a resuscitation guide. I thought it was going to be something interesting like transformer specifications and tap settings.
The old signs are quite fascinating. At least we can surmise that originally there would have been an isolator on the low-voltage side of the transformer somewhere in there.
And what d'ya say folks, shall we send Alan off into the French countryside to find HV isolator no. 4691?
By the way, any idea what the HV level would have been when this was new? And what it is now? Isn't most local HV distribution over there 20kV these days?