Tech ghosts of a lost age, of a lost age ...
Watching Threads again recently I was struck by the fact that some of the only sounds in the most impressionistic later part set ten years after the attack come from pre-attack artefacts such as this video, an LCD video game, a rock'n'roll record. Despite the rediscovery of coal and steam power by this point, people still seem to be in a state of speechless shock, and the factual commentary is given as intertitles and stills.
And of course the randomly surviving artefacts intended to represent contemporary civilisation are now also of another era, which I think gives it a slight extra dimension of bleakness (if that's possible) or maybe just reinforces the effect of time passing without 'progress'.
This is also a much better example of what I was talking about in my comment about Viewmaster and Mad Max Beyond Thunderdome -- the hauntogological aspect of children of the post-civilisation future forming a worldview from randomly surviving fragments. We're not given any indication of how much of the programme the children actually understand, though I always thought there was an implication that the domestic animals shown were probably mostly extinct, and probably unknown to them.
I don't think these kids are going back to Tomorrow-morrow Land either.