Jerusalem! Surely not :-
Nor shall my sword sleep in my hand
Till we have built Jerusalem
In England’s green and pleasant land
I have never been to Jerusalem, but from what I have seen and heard about it, it is about the last place I would want built here. And its music is almost as dreary and miserable as that of GSTQ.
Difficult to know where to begin with the problems with "Jerusalem". A point of issue between Christians, Muslims and Jews since at least its capture by Muslims in 1076, leading to the Crusades, and a flashpoint right up to the present day. And we should have a national anthem about waving a sword over it?
Secondly, even without the political issues, what is a foreigner to make of an English national anthem being about a city in Israel/Palestine (delete to taste)? Imagine - it would be like us hearing that the national anthem of Mongolia, say, is "New York, New York"! You'd think - what the heck ?!
OTOH, Land of Hope and Glory would make a brilliant anthem. I heard a story that Elgar composed the music while cycling in the Shropshire countryside, as he often did, and that when he got back he told a friend that he had thought of a melody which "will knock 'em flat". He was right. I don't generally get excited about music, but this melody was the first I ever remember to have stuck in my mind.