Throughout this GR, I've been trying to puzzle out what JA meant by a "large" party. In ch.3, a large party was 19 people, in ch.39 it was at least twelve and possibly more.

In ch.53, Mrs. Bennet plans to have 13 or 14 people at her dinner table, and from what I can tell, the "large party" who assemble at Longbourn in ch.54 come on the same day she originally planned her dinner party, with lots of extra guests added:

Mr. Darcy was almost as far from (Elizabeth) as the table could divide them. He was on one side of her mother...She was not near enough to hear any of their discourse (snip)

The gentlemen came; and she thought he looked as if he would have answered her hopes; but, alas! the ladies had crowded round the table, where Miss Bennet was making tea, and Elizabeth pouring out the coffee, in so close a confederacy, that there was not a single vacancy near her which would admit of a chair. And on the gentlemen's approaching, one of the girls moved closer to her than ever, and said, in a whisper --

"The men shan't come and part us, I am determined. We want none of them; do we?" (snip)

When the tea-things were removed, and the card tables placed, the ladies all rose, and Elizabeth was then hoping to be soon joined by him, when all her views were overthrown by seeing him fall a victim to her mother's rapacity for whist-players, and in a few moments after seated with the rest of the party. She now lost every expectation of pleasure. They were confined for the evening at different tables, and she had nothing to hope, but that his eyes were so often turned towards *her side of the room*, as to make him play as unsuccessfully as herself.

(Sounds like quite a crowd there! Elizabeth is seated too far from her mother and Darcy to hear what they're saying, Jane and Elizabeth are serving coffee and tea buffet-style, there's such a crowd around the table that there's no room for Darcy, and later, there are so many card tables that Darcy's is on the other side of the room from Elizabeth's!)