I read somewhere that there are different brews of Guinness, depending on how far it has to travel, and only the Irish pint is the original formula. This might tie up with JimmyC's post at 8.59.
Mind you, it would be in Liverpool a sight quicker, and having had a smoother journey, than it would be in, say, Kerry.

Now what was that old joke about the rear-gunner on a Guinness drey?