I've heard this fairy tale for decades, and quite frankly, I'm putting it into the same camp as claims of undeleting data from magnetic media or reading license plates from space --- By that I mean that such things may be theoretically possible, but from a pragmatic and practical perspective, they might as well be complete science fiction.

Please, can anyone find a single concrete example of ENF working? All the information I can find about the UK's supposed widespread and automated use of it starts to evaporate into the same kind of conjectural nonsense as polygraph tests.