1978 is a pretty good time to stop collecting the stories of Doris Lessing for publication. That’s not to say that she didn’t continue to write and write well thereafter (though I am waiting to read a few more things post 1980 for her to see exactly what she did write), but in the late 1970s is when she really dove into her science fiction phase with the Canopus at Argos books (which I actually love in their strange imperfection) as well as her Jane Somers books, an alter-ego/pen name, she used just to test out the publishing world. She also would be writing more overly political fiction and nonfiction in the 1980s and 1990s, and from what I have read there, I found it decidedly mixed. So!
This is a very strong collected stories. She’s not primarily known as a story writer, but her stories are often masterly. She comes off as a novelist working in a different venue, but it’s clear that she’s working earnestly and exhaustively to figure out the story genre. Some of the stories run quite long, and most are publication length (5000 words or so), and because there’s a separate book collecting her African stories, these do tend to be domestic to England of the 1950s-1970s. That’s all good too, as The Golden Notebook and other novels she wrote in the 1960s and 70s showed that her growing up in Rhodesia is a compelling part of her narrative, but not the source of her genius. It’s more Doris Lessing, working in her prime, if that’s what you’re into.