Ah, the good ol' days. Actually, they're probably called that because the whiskey (or "whisky" for all you purists) made you forget all the bad parts ... The Whisky Vending Machine, which mixes whiskey and soda, above was shown at the Second Automatic Vending Exhibition in London, 1960.
See also: Strange and Wonderful Vending Machines
Being a fearsome snob, like all good Englishmen, I've always viewed someone calling it "scotch" as being a pretentious ignoramus, attempting familiarity with a noble liquor and only managing to reveal their dismal lack of sophistication, who deserves only the cheap stuff and a miserable hangover.
That is all.
I don't know if it's an english idiom (they certainly use it a lot)
but there is nothing like a scotsman ordering a whisky in london and being given jack daniels, and when pointing out that you didn't want a bourbon, they say .. oh why didn't you ask for scotch....