I've recently come across a sample of Teacher's from the 50s or so, which is labeled as 86 proof. I recalled US proof (2x ABV) was not the same as proof in the UK (at least until 1980 according to Wikipedia
I just wanted to see if someone could confirm my understanding here...
this, being bottled at 86 proof * 4/7 = 49.14 so about 49% ABV?
Just wanted to make sure I am understanding this correctly.