...but if he refers to Mrs. Hurst as his eldest sister, then she would be the oldest of three or more sisters ("elder" would be comparing the ages of two sisters). So likely, there is a young Bingley sister who may not be out in society yet, or at least is not currently staying with Mr. Bingley. This still does not help us to figure out comparative ages, as Mrs. Hurst could be the eldest sister and yet even be younger than Bingley. (He's probably 22 or 23 as an earlier post said. Mrs. Hurst could have entered society at age 18, got married and be 20 or 21. Miss Bingley could then be early out in society, say 18 or 19.) I would guess that Mrs. Hurst is older than Bingley, but it is difficult for me to place where Miss Bingley is. P&P2 always makes me think she is older than Bingley, but the book doesn't necessarily give that same impression. The book makes me think she is close in age to Jane (i.e. 21).