Atticus suspects that the Old Sarum gang will try to harm Tom Robinson before the trial, and he plants himself outside Tom's cell before the racist lynch mob shows up. Scout smells whiskey on the men as one of them grabs Jem, and she kicks him for doing so. The scene is growing increasingly tense when Scout is able to connect with Mr. Walter Cunningham on a very personal level. Scout reminds him in her innocent, childlike way that Atticus has helped out the Cunningham family in their times of need and that she and his son go to school together. These efforts give Mr. Cunningham reason for reconsideration, and he instructs the group to leave.
In the next chapter, Scout assesses the jury and notes, "One or two of the jury looked vaguely like dressed-up Cunninghams." The chance to have a fair jury for Tom in Maycomb is a fairly impossible feat, but Atticus has realized in his jury selections the innate sense of fairness in the Cunningham family.
After the verdict, Atticus tries to explain the legal process, with all its shortcomings, to an upset Jem. Atticus explains that there is a small victory in the deliberations because "there was one fellow who took considerable wearing down—in the beginning he was rarin' for an outright acquittal." When Jem questions which juror could have possibly defended Tom, Atticus tells him that "he was one of your Old Sarum friends."
Jem guesses that Atticus means a Cunningham, and Atticus says that he was "one of their connections." And on a "hunch," he hadn't struck him from the jury selections. The Cunninghams are a resolute group, and Atticus tells Jem that if they'd had two Cunninghams on the jury, there would have been a different outcome for Tom.
This small victory shows that even the most racist people can be touched by goodness and can change their views. Perhaps the Cunninghams saw truth in the words of young Scout's innocent observations, and perhaps they were open to the truth, regardless of a man's skin color. In either case, a little hole was knocked out in the wall of racism in Maycomb.
In Chapter 15, the Old Sarum bunch surrounds Atticus while he is reading outside of Tom Robinson's cell. They are a lynch mob who plan to kill Tom Robinson before the trial. Fortunately, Scout unexpectedly runs out into the circle of men and attempts to have a conversation with the familiar Walter Cunningham. She catches Walter's attention, and he is able to see the situation from Atticus' perspective. Walter tells the rest of the Old Sarum bunch it's time to leave, and the mob drives away without harming anybody.
Following Tom's wrongful conviction, Jem loses his innocence and becomes jaded about the community members of Maycomb. In Chapter 23, Jem is discussing the trial with his father. They begin talking about juries and Jem wonders why no righteous people such as Atticus or Maudie ever serves on them. Atticus tells him that Maudie can't serve on a jury because she's a woman, and the other upright community members are too scared that their decision will affect their reputation. Jem comments, "Tom's jury sho' made up its mind in a hurry" (Lee 297). Atticus disagrees and says to Jem and Scout that there was one fellow who "took considerable wearing down" and was arguing for an outright acquittal. Atticus doesn't say the name of the person but tells them that he was part of the Old Sarum bunch. Jem is shocked that one of the Cunninghams was in favor of Tom Robinson, considering the fact they tried to kill him the night before the trial. Jem says, "I'll never understand these folks as long as I live" (Lee 298). Atticus explains that once you earn the Cunninghams' respect, they are for you tooth and nail. He surmises that they earned their respect by not backing down in front of the jailhouse that night.
Even though Tom Robinson was still wrongly convicted of raping Mayella Ewell, there was a moral victory in getting one of the Cunninghams from Old Sarum to argue for his acquittal. Changing the mind of a violent racist illuminates the slow changes taking place in Maycomb in regards to racial injustice.