> the rest of the world uses 24hrs, however 12h _sometimes_ is used conversationally;

Here in Norway we use 24 hours when writing; but we use 12 hour system when speaking - if that makes any sense?

I.e. we would say: "Vi spiser middag klokka fem (5)" [We eat dinner at five o'clock]; but we'd write it with 17 typically. We never use the terms AM/PM but can occasionally specify daytime/nighttime if it's uncertain which of the two we are talking about. I.e. "Jeg kom hjem fra jobb klokka fem (5) om morgenen" [I came home from work at five in the morning].