I've noticed the British practice wavering for a while now. For example, large buildings such as hotels often number their rooms using the floor number as the first digit, and those numbers are usually number American style. Naturally this causes confusion.
Anyway, just as paleontologists particularly value those fossils that show an organism caught midway through an evolutionary change, I was interested to see this barber in Clifton the other day. First, let me show you (courtesy of Google street view) what it used to look like:
As you can see, this three-storey building mentions a first floor (upstairs) and also a top floor.
More recently, an extra sign has been added:
Now, the building is divided into Ground Floor, First Floor and Third Floor.
Whatever happened to the second floor? I suggest that it has been lost in the crack between two numbering systems. The barbers knew that the bottom floor was the ground, and they knew that the floor above that was the first floor. But, rather than extent that system indefinitely, they thought, "Oh, that's three floors up, so it must be the third floor."
I don't say this is interesting, let alone important, but I think it's kind of neat.