Well... my family have contact with english people and everyone of them has a lot of alcohol tolerance. More than many germans. Indeed they make jokes about the germans (I'm german descendant) get drunk easily while the english would never suffer it (at least as quick as germans I think).
And you have a huge advange: irish, english or scottish have a natural genetic predisposition to drink high amounts of alcohol without much harm. The references: National Geographic Channel or Discovery.