I am writing in 2 parts tonight as I still haven't managed to stop the screen rolling up if I write too much...
As I understand it, Quartet In Autumn was written late in BP's life, when she already knew she was suffering from terminal cancer. I suppose it is more than likely that this coloured her view of the world, but it is also possible that she just wanted to examine a different aspect of it - instead of the comfortably affluent (Some Tame Gazelle, A Glass of Blessings) or the comfortable-ish (EW, No Fond Return of Love), she perhaps wanted to look at the position of the unmarried and unmonied in the 1970s.
I don't find it nearly such an enjoyable book as EW, but it is still a good book, and its observations are, IMO, spot-on. In our property-obsessed society, it is perhaps hard to imagine retired people who don't own their own home, but they are out there, and this novel shows just how much that fact can affect your whole life. My mother used to work with a very eccentric older lady, who had been born into the aristocracy; she and her husband had decided never to buy property, as he worked abroad a lot and she, having no other ties, went with him. Husband then died young-ish, and she was left in "genteel poverty", living in a poorly heated, dilapidated flat and without the resources to do anything much about it. It's really awful how much not owning bricks and mortar can matter, at least in this country.
Rosemary