Who spearheads the search for Lydia after Mr.Bennet returns home in defeat?
The search for Lydia continues with the help of Mr. Gardiner who is Mrs. Bennet's brother. Of course, the real engine behind the whole search is Mr. Darcy, it is he who looks for Wickham and Lydia, it is Mr. Darcy who pays Mr. Wickham off so that he will make Lydia Bennet an honest woman.
``My father is gone to London, and Jane has written to beg my uncle's immediate assistance, and we shall be off, I hope, in half an hour. But nothing can be done; I know very well that nothing can be done. How is such a man to be worked on? How are they even to be discovered? I have not the smallest hope. It is every way horrible!'' (Austen)
Darcy shook his head in silent acquiescence.
``When my eyes were opened to his real character. -- Oh! had I known what I ought, what I dared, to do! But I knew not -- I was afraid of doing too much. Wretched, wretched, mistake!'' (Austen)
It is Mr. Darcy who attends the wedding of Lydia and Wickham to make sure that he marries her.
Although Mr. Gardiner spearheads the search for Lydia, it is Mr. Darcy who makes sure that the situation reaches a proper resolution. And, he wants no credit or recognition for his actions.
In fact, he doesn't want anyone to know that he was behind the whole event. He wants everyone to believe that Mr. Gardiner took care of the matter, a family matter.
It is only when Lydia accidentally mentions that Mr. Darcy was at her wedding, surprising Elizabeth with the information that she becomes quite worried after she hears the news.