Patriotism - it's just not a word that's in common use in the same way. It evokes in me a sense of history, or the feeling that the context is American. It's not a dirty word, just not one we use.
"Britain First" were just another bunch of thugs, of which we get a roundabout of many. The guy selling stuff with the British flag on it didn't get into any trouble at all. Some people off the street commented on the name of his shop for reasons connected with the above. You're allowed to do that in Britain, comment on things. I mean he called it "Really British". That's not a very British thing to do is it.