Though I read this book more than forty years ago, many of the questions it raised in my young mind still ring true and still remain unanswered. The premise of the story is that a celebrated astronaut goes into orbit to conduct an experiment in suspended animation. This goes wrong, and he "wakes" up to find himself orbiting a planet that has radically changed. On returning to it, he finds that all of his attitudes, tastes, courtesies, appetites and assumptions about "right and wrong", have been replaced by more gentle and environmentally kinder alternatives. I don't remember how it ends, but I do recall that when asked about the total number of people living on the planet, his reply scared the wits out of the questioners..
I must have read it in the 60s or 70s, long before environmental campaigns and political correctness were "things" - so Eric - C Williams was either a prophet, or a time traveller.