On this morning’s visit to the house, I found the electrician had left a “gift” for me. I think it’s taken from the bathroom, as it’s the only location I can think that had this type of light fixture.
The black plastic cap/strain relief is slagged. The chocolate block/terminal block is completely melted, with the plastic turned brown and bonded to the terminal metal. The wire/plastic close to the terminal block is rock solid, won’t bend. The brown twin-and-earth mechanical protection layer is blackened and damaged.