9/13 National Anthem Played at Changing of the Guard in London on September 13, 2001 and Queen Elizabeth II gave the permission for it. Check out the video below.
She did this to honor the United States of America from the attacks that happened on 9/11 (September 11, 2001).
Queen Elizabeth II gave the permission on September 12, 2001 for the Guards to play the National Anthem, also known as the Star Spangled Banner.
Witness say there was a hush when the Guards began playing the National Anthem, then you could hear some in the crowd starting to sing. There were many Americans trapped in England when the attacks happened on America. That were present to watch this unfold.
Again this was on On September 13, 2001. London is 5 hours ahead of us. They do Changing of the Guards at 11:00 a.m. their time. It usually last 45 minutes. So that would be 6:00 a.m. Eastern time.
Thanks Queen Elizabeth II!