Who is Shaggy Beard from Catherine, Called Birdy and what is their importance?

Unlike Catherine's father, Shaggy Beard has few redeeming qualities. He is the man Catherine is supposed to marry; he is lewd, vulgar, and much older than Catherine. He sends many presents to her when they become informally engaged. He is apparently quite cruel to his son Stephen, who is about Catherine's age and who is much cleaner and more learned than his father.