A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
From: Frank Reed
Date: 2019 Jun 10, 09:07 -0700
The change was not formally adopted until Jan. 1, 1925. It's even in your chronology:
"1925: GMT adopts Civil Day convention, day begins at midnight 00AM-12noon-24PM but word "Civil" never added to GMT "
...which reminds me, your chronology is a mess of trivia, real history, and odd irrelevant items. It's full of weeds and needs a good pruning! If even you can't find the useful material in it, then something has gone wrong. Please take an axe to it and get rid of at least three out of four items. Thanks!
As for your time sight calculations not working out, this is one of those things that separates the classroom from real navigation. This sort of error would never happen in the real world.