The way I get around this in my head is that UK's timezone is "Europe/London". (my definition of "timezone" is "IANA timezone", so while "UTC" or "GMT" are both

The way I get around this in my head is that UK's timezone is "Europe/London". (my definition of "timezone" is "IANA timezone", so while "UTC" or "GMT" are both valid, they aren't what the UK uses.) The "GMT" or "BST" is just a locale-ish thing that gets tacked on to output, much like "EST" or "EDT" for "America/New_York".