I was about to laugh at you for not realising that Netflix's House Of Cards is actually a remake of a BBC series from 1990, but on reflection that probably adds to your point.

Many British films of the 1950's and 60's (also being non-rigorous!) are morally very black and white, lots of war movies, but also things like the early James Bond films have an absolute faith that Britain was a world power, maybe alongside the US and USSR, but still important, whereas by the late 1980's that self confidence had pretty much gone and instead you get the shades of grey and cynicism of things like House Of Cards.

Of course Britain's loss of empire was much more definitive then any US decline, which is mostly a post-9/11 post-iraq war loss of confidence but there is an interesting parallel.

Most programmes are a commentary on the time they are made, not the time they are set so I agree deep reads can be very revealing.