The Tom Collins was originally made with genever, so this is the original Collins. However, old tom gin replaced genever on a Tom Collins, relegating genever...
Still trying to get my head around genever. Agree with JH’s description below re the sour note - reminiscent of sourdough. Tried directly after the classic Tom Collins, which I think I prefer at this point. But nonetheless tasty and refreshing.
I find "genever is like gin" comparisons quite strange, because they taste nothing alike. I liken jonge genever to vodka where the primary flavour is a minerality and a lot of nothing, and oude genever to a lighter scotch.