State - SW England & Catholic - NE Scotland. I'm not sure? But I first started (outside of school) on a typewriter, and terminals were all fixed width (Acorn, Amiga, BBC) - which the argument goes is where it came from (although the typesetting comment by @OliverJones suggests otherwise).
I wonder if perhaps it was just a function of the teacher you had? The world was less connected (even now parts of education are individual preferences rather than rules). Oxford comma, punctuation inside or outside brackets, etc vs et cetra vs &ct