Jerusalem was used at the Commonwealth Games, so England have their own, and NI have Danny Boy then - though GSTK at football.
Hmm - I think you know my views about the Commonwealth games and more of that below.
I was thinking more about singing the anthem before a match involving international sides - so the England football and rugby sides don't sing Jerusalem, although I was at the ashes and it was sung there.
What do you suggest gets played at the Olympics in place of GSTK?
I know this is a bit ducking the question, but I don't think the Olympics (nor the Commonwealth games) should be contested on the basis of countries as most (albeit not all) of the sports are individual. So Usain Bolt is fundamentally competing as Usain Bolt, not as 'Jamaica'. That would only really make sense if there was only one competitor representing each country, but that isn't the case.
So I'd do away with flags and anthems at the Olympics as I don't really understand why Andy Murray wins Wimbledon as Andy Murray (no national anthem played) so why doesn't he just win the Olympics as Andy Murray.