Under the general heading of “Oh, so that’s what it is! I never realised,” picture this.
It’s late 70s/early 80s Britain. You can’t sleep, so get up at some infeasibly early time, grab your morning stimulant of choice and settle down in the lounge to see what’s on TV. Not much, in this pre-dawn, pre-breakfast-TV scenario. Pages from Ceefax of course, and flipping over to BBC2 you hear the familiar strains of…
Oh, that’s actually a piece of music? Wow!