"we'll meet at four your time"
"great!"
"why weren't you there?? I googled 'current time utc!!'"
"because we're on BST, aka IST, aka UTC+1 in the summer"
But this rando website says UK/Ireland is UTC!!
Someday, somehow, we'll teach people that if you're using PST in the summer, there's a 99% chance you're wrong.
The Olson TZ data works on cities (e.g. "Europe/London" or "America/Los_Angeles") but more importantly because a city has all these humans living in it there must actually be a real working answer, or it'd be chaos. Even if the person you're speaking to isn't _from_ or working/ living in the major named city, they will have a better idea what the time is in nearby major cities than how timezones work around the world. Nobody in, say, Nantes is confused as to what time it is in Paris but they may be unclear about PST vs PDT.
It's unfortunate that the two systems aren't in sync, but they were developed in parallell and have different data structures.
It doesn't actually make a difference. We still switch at the same time that the rest of Europe does.
In my experience, people in the UK refer to their time as "GMT" all the year round.
Putting the Republic of Ireland and Northern Ireland in different time zones would be.. annoying, at the least.
Then again you said Britain, not the UK, but I can imagine the DUP protesting pretty loudly if NI were in a different timezone to GB.
Nomenclature is fun.
Accidentally.