Thanks, Wodehouse was right but Psmith likely wrong. I read the entire Wodehouse oeuvre when in my early 20s...perhaps Psmith had a friend who was a golfer. I'm not a golfer but liked the Oldest Member stories, didn't care for the Psmith works.
23d - "Quite the reverse" refers to the fact that the 2 abbreviations for "rule" go inside the PM rather than the other way round so instead of the 'PM breaking rules' it's the "reverse" with the 'rules breaking the PM'
What would have worked better in that spot would be a homophone of another horror star, married to a former (how long ago now?) PM but that would probably have been too much for the Guardian woke tofu-munching anti-growth coalition I think.