I have a telly though. Herr TV van Detector can see that through the window (as the path to the porch and front door goes right by it). There's not much detecting to be had on that score. There's also a ginormous aerial (and satellite dish) on the side of the house (as I live on the side of a steep valley). But I don't watch terrestrial TV, just DVDs and Amazon/Netflix. I am a child of the future, DVDs aside. I wear shades indoors. I'm that cool. Either that or the heating's off.
The aerial isn't connected to the TV (it's not connected to the socket, the coax is just coiled up where it appears in the cupboard of ineffable mysteries in the annex to the asbestos palace). So I guess I could invite Herr van Detector into my house (generally I'm wary about this, I spend a lot more of my day than the average person worrying about vampires) and shove him into the cupboard. There's no actual handle on the inside, if I recall, so I might forget to let him out (I was going to say her, but locking ladies in cupboards is frowned upon, and usually a segue into an Hollywood movie featuring Morgan Freeman and, oh, it going to get complicated).
I'm not sure what he'd be proving, I could – even with my limited technical competence – uncoil the cable and scrabble it back into the arse-end of the socket and have the TV sucking up terrestrial TV quicker than a zombie with a bucket of brains and a straw.