When Mr. Gardiner writes his letter to Mr. Bennet about Lydia marrying Wickham, he writes, "You will easily comprehend from these particulars that Mr. Wickham's circumstances are not so hopeless as they are generally believed to be. The world has been deceived in that respect; and I am happy to say there will be some little money, even when all his debts are discharged, to settle on my niece, in addition to her own fortune."

I'm wondering why Mr. Gardiner doesn't just tell Mr. Bennet the truth, or some portion of it anyway. Here are the options he has, as far as I can see (maybe you can think of more):

1. Let Mr. Darcy pay off the debts, then paint Mr. Wickham in a much better light than he deserves by acting like there were fewer debts, intrigues, etc. than have been rumored (which is what he did)

2. Let Mr. Darcy pay off the debts, then explain to Mr. Bennet exactly what happened, and tell him not to tell anyone else

3. Let Mr. Darcy pay off the debts, then tell Mr. Bennet that the debts have been discharged, without getting into specifics (i.e. -let Mr. Bennet read between the lines)

4. Pay off the debts himself, then tell Mr. Bennet that Wickham was an honorable man who made a mistake with Lydia, but not mention the debts at all

5. Pay off the debts himself, then ask Mr. Bennet to help him by paying at least some portion of it back