When the painting is revealed
I cry every single time. Although, I must admit, I watch the film mostly for the love story between Belle and Mr. Davinier, I always shed a tear when Dido finally sees herself and Elizabeth standing next to each other on canvas. In many ways, this was a love story for Dido and Lord Mansfield--he knew that he loved her like she was created of him and Lady Mansfield, but Dido was not completely sure of her position. We see Lord Mansfield making gestures and accomodations, but Dido misinterpreting them...and that's certainly understandable...I believe though, by the end of the film,that she realized how much he loved her and this was just as much a victory as was the Zong case.
If you can't be good, at least be good at it!