It's an interesting selection, this lot. Thames doesn't appear, for one thing. https://www.youtube.com/watch?v=ztseBSHLNic
Includes a "different times" Les Dennis Scottish accent for STV which isn't replicated when Grampian comes up, presumably because he's no idea where that is.
Taking it at face value, it's not a huge leap to guess there will be a station called Scottish and people probably knew it from Taggart. Grampian sounds odd so probably sticks in the brain to the few people who knew it.
Les is particularly charitable accepting answers here tbh. York TV?
Indeed, they wouldn’t allow York TV on Pointless. I’m not sure he should have given “South” either.
Thames not even being on the board is just bizarre, I’m sure to those people who were around at the time, their pre programme ident is still remembered even now.