Peter Frimberly wrote:

When I lived in Newcastle (admittedly 15 years ago) it was a fairly
standard occurence that the Metro line would be closed for a few days
on one of the sections around Longbenton, Wallsend, or Pelaw, because
someone had hooked a landrover to the signal cabling in the troughs or
the catenary and pulled massive lengths of it out/down in order to
steal it for scrap.

I don't live there any more so don't know if it still goes on.

Presumably not, in those days scrap metal was worth something!