Old B&W movie, juror says Not Guilty and everyone laughs

Hi all, I need help tracking down a movie based on one scene I remember from watching TV in the very early 1980s. I might have been three years old. It's in black and white, probably the 1950s or 1960s (if not even older), and I think it was made in Britain. I think it was set in the 19th century. The scene involves jurors individually giving their verdict in some trial or other. One after the other, each of them says "Guilty" (there must have been the standard 12 of them, there were a lot of "Guilty"s!), until one of the jurors says "Not guilty", whereupon everyone in the place explodes into laughter. And... that's all I've got! Help!