Swing dancing, 1939.
99% certain this is footage from the 1939 World’s Fair at Corona Park in Queens, NY (note the national flags in the background of the bottom two gifs and the artwork and statues on the building in the upper right gif).
"John Cleese was flirty, Michael Palin was shy, Terry Jones very jolly, Eric Idle a bit aloof, Graham Chapman very polite, Terry Gilliam loud and manic." Carol Cleveland
Song: Have I The Right
Band: The Honeycombs
Album: The Honeyombs (1964)