I always thought of “Briton” in that last sense, while “Brit” has the meaning of anyone living in the UK (almost). But that’s from an outsider’s perspective.
As my English cousin corrected me, though, “I’m English, ‘British’ could be anything!”. She wasn’t, of course, talking about the difference between English and Welsh, or Scots.
Many, many years ago I used to have two Wyse50 terminals, running split screens each with two parts. I did a lot of support on remote systems (via modem!) and I would have a session on a customer system, source code and running on our test system and internal stuff. I didn’t have space for a third terminal.
At another job I had an office with a “U” shaped desk. I would spread printouts across half the “U” and swivel around between the computer and the printouts.