My only quarrel with Amazing Grace was a musical one. The Newton poem was not associated with the tune “New Britain” until the late 19th century, and that in America, but was sung to almost any Common Metre tune. Wilberforce’s singing it at the gambling club and the congregation singing it at his wedding to “New Britain” was anachronistic.
Yes, I’ve heard this. I can’t say myself that this would be my only quarrel with the film — partly because I have other quarrels, but more because I wouldn’t quarrel with the film over this anachronism.
Anachronism is not always an artistic sin. To take an extreme example, films set in the ancient or medieval world typically depict the characters speaking in the modern language of the filmmakers and their audience. This is generally understood to be a necessary bridge between the material and the cultural context of the audience.
To have “Amazing Grace” sung anachronistically to the tune by which it has been universally known for decades represents a not entirely dissimilar situation. To use any other tune would create a deep disconnect for viewers in a film that is very much aware of its audience. A high-minded music-history literacy advocate might consider it a “teachable moment,” but the filmmakers would be within their rights to consider the historical point not worth the loss of the well-known tune and its deep-seated cultural significance, certainly in American consciousness.