IMO Darcy's courteous treatment of Wickam in the Letter is not only a feature of his character, but also a product of his background and education. On the reverse, we may remember that the Bingley fortune is quite recent. Although Charles' amiable qualities and good heart save him from snobbishness, is is not so with his sisters. Caroline's treatment of Wickham seems to show, in my eyes, how much of an upstart she is.