I agree with EH, Rule Britannia is largely regarded as our no 2 here, but Land of Hope and Glory and Pomp and Circumstance are more or less equal imo (and in fact all four get a run out at that most British of British institutions - the quite wonderful Last Night of the Proms).
I take your point - they all seem quintessentially British, so it's strange (or sometimes worse!) for us here to see them elsewhere.
For me, though, after hearing Auld Lang Syne blaring out in shops when it's near closing time in Japan, nothing surprises me anymore!!