Maud Cairnes (1893–1965)

A fascinating example of what I think of as "domestic sci-fi," very much in the realm of Frank Baker's Miss Hargreaves. If you like the idea of fantastical happenings but still enjoy keeping your feet firmly planted in the polite world of drawing rooms and house parties, this 1930's body-swapping tale of two women from different social classes is for you.
It's neither overly comedic nor dramatic, but treads a nice middle ground. I read it in one sitting.
Newly republished this month (March 2022) and also available on Kindle Unlimited.

Fun quote:
Foley put me into an evening dress made of black velvet that showed a lot of back. It seemed rather plain to me, I looked very slim and straight in it. She then opened a big jewel case in which there were several tiers. I thought it looked like a real treasure chest, when I saw brooches and necklaces, bracelets, earrings and rings, all in velvet compartments. I just stared. Late for dinner or not, I had no intention of hurrying over my choice. I took a sort of collar of emeralds and diamonds, and put it round my neck; it looked wonderful. Then I found some emerald and diamond earrings, long ones, and some bangles; I put on two or three of these and a big diamond brooch like a spray, that cheered up the dress a lot.
Then I saw the pearls--three long ropes of them--and one shorter one. I put the ropes on and looked happily at my reflection in the mirror.
"I think I want something on my head now," said I, wondering if it was a grand enough party for a tiara.
Foley, who had been looking rather stunned, smiled respectfully as though I had made a joke. I gathered that it was not a tiara occasion.… (meer)

Polly, a middle-class housewife with two small children suddenly finds herself in the body and life of Lady Elizabeth, a childless, married woman much higher up the social scale. It's only temporary, and Polly returns to her life to find that Elizabeth has been in her place, playing with her children and puzzling her husband. From time to time, unpredictably, Elizabeth and Poly swap bodies, surprising friends and family with odd behaviour caused by the different rules they've been brought up with, and their unfamiliarity with the people and places surrounding them.

A charming, gently amusing, good-natured book.… (meer)