A 1942 British Ballroom.

This is from the wartime film "Listen to Britain". I extracted the ballroom scene since it is such a marvelous survey of British ballroom dancing of the '30s and '40s. Note the wide variety of skill levels (the better dancers seem to be near the center of the room), the fact that they are foxtrotting to a Polka, their strict adherence to line of direction and the fellow in the middle in formal wear whose job seems to be to keep traffic moving