I'm pasting the whole paragraph here because it is short:

"And mine," added Sir Walter. "Kindest regards. And you may say that I mean to call upon her soon. Make a civil message; but I shall only leave my card. Morning visits are never fair by women at her time of life, who make themselves up so little. If she would only wear rouge she would not be afraid of being seen; but last time I called, I observed the blinds were let down immediately."

Elizabeth and Sir W are sending "love" (ah, the irony here!) to Lady R with Anne. What I think about the end of his sentence is that MAYBE (probably!) Lady R had "the blinds let down" because she didn't want to see Sir W, and is pretending to not be home, NOT because she was afraid of being seen. What does any one else think?