Discuss Gamfield, the chimney sweep. Why does Dickens include him in the story ?

I believe that Gamfield was meant to show another side to the abuses of children by marking the way in which these children were treated. Gamfield was not a nice man, and though he himself suffered from poverty and indebtedness, a mere five pounds could bring him to the workhouse door. His actions had already caused the death of several of the young apprentices he'd overseen. Now he was in a position to get paid for doing the same to another. Gamfield needed five dollars for his rent, and Oliver would afford him free labor.