Zix, you'll just never get it, so no, we can't explain it in terms that would make sense to you. In your tradition the national flag is roughly the equivalent of the contenders' towels in a boxing match, used to signify the forced change in title of ships when one side has had enough, which was usually the French until you ran into our derisively-nicknamed "Fir-built frigates" like the USS Constitution in the War of 1812's frigate battles. To you, the Star-Spangled Banner flying bravely after a night of bombardment at Ft. McHenry was just an indication that your mortar and rocket aim wasn't quite what you wanted in accuracy, but to us it was ever so much more than that, and you simply would not ever get it.
The closest equivalent you really have is the military tradition of safeguarding the regimental colors at all costs, down to the life of the last man standing. Of course so few Englishmen currently in public life have actually served their country's military with devotion, vise time-serving in unimportant peacetime duties, that the example is no longer really meaningful for you, particularly considering you are apparently a Progressive buffoon who views the world through the lens of Monty Python silliness in the first place.
And I mean no insult to the good and true Brits who remain, imperiled with extinction as they sometimes seem to be, such as our own beloved Bijou or the 'Foot, horse and marine' serving almost thanklessly in far-flung corners of the world to uphold the right.
No Zix, you just wouldn't understand.