As you might already know from our analysis of Lady Brit, Charles is kind of a goofball—he's usually laughing or saying something when he shouldn't. These tendencies make him the frequent whipping boy of Lady B, who finds his inability to behave properly quite frustrating. When she is chatting with Stephen about the mates her daughters have chosen for themselves, she suggests she has zero confidence in her future son-in-law's ability to grow the family fortune through his own industriousness:
Charles Lomax's exertions are much more likely to decrease his income than to increase it. Sarah will have to find at least another £800 a year for the next ten years; and even then they will be as poor as church mice. (1.31)
That said, Sarah seems to like him, so we guess that'll have to be good enough for us? Plus, he really does provide Lady Brit with the opportunity for some great zingers, so we love him just for that.