While the old TV show UFO had many flaws, it did tackle some serious issues. The latest episode of my rewatch of the series dealt with what the Machine on Person of Interest would classify as an irrelevant number. Spoilers obviously.

The episode "The Square Triangle" concerns an unfaithful wife and her lover planning the death of her husband. They're going with the "I thought he was an intruder so I shot him" routine but through a contrived set of circumstances the wife ends up shooting an alien instead of her husband. The pair is drugged to erase their memories of the alien and SHADO. But the leadership of SHADO figures out the murder plan and realizes that the two will almost certainly try again to kill the husband. Should SHADO try to warn or help the husband? The commander of SHADO says no, it's not their problem. The episode ends with the wife looking at a cemetery headstone.She walks down a path and meets her lover. The clear implication is that they succeeded in killing her husband.

Anyone who has watched Person of Interest should recognize that the husband is just the sort of irrelevant number that the Machine would find and give to Finch. But this is long before the surveillance society kicked in so the husband is unknowingly doomed.

So far in my rewatch of the series there has also been interracial romance (I'm not up on how that was viewed in Britain in 1969 though) and looks at the personal costs of working for a secret organization. I like that UFO will go with the darker tone when it makes sense and that choices have consequences.