Out of curiosity, we still have original Victorian sewers and rail way works. Is there any Victorian copper wire left still operating in the ground? (I presume anything overhead would have fallen down by now?)
Not Victorian, AFAIK, but there is still a fair bit of lead covered cable in use. Not sure when they stopped using that, perhaps some time in the 1950's or 60's, but it's far from unusual to find a lead covered incoming underground cable. My guess is that there is still a lot of this stuff around. Same goes for VIR wiring in houses. They stopped using that at least 50 years ago, but you still regularly find it still in use in older houses.