09GMT-09GMT for my manual readings that I use for my records and 00-24 for my DVP which I use for rain intensity etc
00-24 makes more sense to me, but I followed the standard convention here
24 years ago. Work shifts still allow for these obs times.
If I was just starting to keep records I'd go 00-24. Makes more sense to me
09 obs on a foul Jan morning not exactly fun.

Ian Raunds E Northants