That's Cagney as prototype singer-songwriter George M Cohan in a scene purporting to recreate the first night of Cohan's show George Washington, Jr. It wasn't quite like that on stage, but that's where "You're a Grand Old Flag" was introduced to the world - at the Herald Square Theatre in New York on February 6th 1906. In the course of the number, he took a flag and, head cocked to one side, marched it back and forth across the stage - a routine the crowd loved so much he repeated it, to one tune or another, in many subsequent shows (and, via James Cagney, in that smash hit Forties biopic). But this song was special. Cohan saw himself as the embodiment of the American spirit.