From where I lived, just the lager and cider together was snakebite, and with blackcurrant it was a “snakebite and black” - but I think there was a lot of regional variety (in the UK, at least).
I have heard lager/cider/blackcurrant called a snakebite before though (I remember it causing a disagreement in the pub) - but I’ve also heard it called a “diesel” (which elsewhere was something mixed with guinness). I’m pretty sure you sometimes got different things in different pubs in the same town.
I suppose pre-internet, we were just relying on the drunk people ordering things to decide what they wanted to call stuff (“what was that purple mixed drink called that made me throw up on my own shoes?”).
“The Darkness Out There” by Penelope Lively.
In short, a “nice old lady” tells a couple of young kids about what they did to a young German who survived a plane crash over Britain during WW2.
I think it was there for the “the nice old lady was actually nasty and cruel and the evil nazi was actually just a scared, fairly innocent boy”.