[gnabgib]

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

[marcus_holmes]

I had an Acorn Atom (still have it, though I can't get it working any more). Nothing in there suggested 2 spaces after a full stop ;) And the manual used to talk about the "computer programme"!

I guess it's down to teacher and style, as you say. I find it interesting that I never met this until post 2000 internet forums with Americans, though. I wonder how widespread it is.

And like tabs vs spaces, I get that there's a "this is the way" answer. Tabs are the right answer, and anyone who says spaces is an idiot. But 2 spaces after a full stop is clearly the right way, but I'm buggered if I can bring myself to do that ;)