I've never been to a pool party

Well I haven't been to a pool party for a long time, and it was a pretty small pool.   Back in the 1970s when I was of an age to enjoy these sort of things pools were a rarity in London, I would say that they still are.   I do wonder if I were invited to one now how would I dress for it?   The thought was inspired by today's Leanne which I felt I just had to share