Mid- to Late 70s Margaret Drabble Penguin book covers, with photography by Chris Yates
A Summer Bird-Cage (1975 reprint) and The Millstone (1977 reprint) are my scans (although I'm aware that they appear elsewhere on the web. The Ice Age (1979 reprint) is via Keir Hardie (scatterkeir on Flickr) and The Waterfall (exact year of reprint unknown) is via Brickbat Books.
I think they make a lovely set. If anyone knows of any others in the series, please let me know!