Nonsense; those who live on the west side of the pond speak a language quite distinct from that of the Anglophone British (although not quite as different as it is from the languages of the other British). This was pointed out quite clearly by Oscar Wilde (an Irishman) in 1887, approximately 55 years before various historians of English literature claim it was first notice by Bernard Shaw (who of course was another Irishman, although the English chauvinist journalists who wanted to award him responsibility for that discovery were probably not aware of that - they'd surely have picked someone else if that had been).

Thinking of that has reminded me of Shaw, and almost I'm tempted to change my sig. But I don't think that the Shaw quotation "I have defined the hundred per cent American as ninety-nine per cent an idiot" would go down too well as a sig at all, because the very thing that would make it an amusing quote (that most people would take it as applying to all Americans, instead of just to one particular person) would mean that most people would take offence at it.