Who is William Bush from Flying Colours and what is their importance?

When we meet William Bush, we learn that he and Hornblower have been serving together for seventeen years. Bush is described as tall, courageous, and extremely strong, as well as honest and dependable. When he loses a foot in battle aboard the Sutherland, his constitution pushes him forward to recovery, after which he quickly learns to maneuver on artificial leg. During the novel's conclusion, Bush is promoted to Commander.