I have written a post for our Hearing the Movies blog in which I discuss the film On the Beach (1959): link. Ernest Gold (best known for his music for Exodus) composed the underscore, and the familiar song "Waltzing Matilda" plays a prominent part (the film is set in Australia). In the post, I comment on four instances where the ending rises rather than falls. Gold makes very striking dramatic use of this alternate ending in the film's final moments.
The point of interest here is how easily the change in the melody is made and how natural it sounds.
