Do not imagine that your picture of your tête-à-tête with Sir B. makes any change in our expectations here; he could not be really reading, though he held the newspaper in his hand; he was making up his mind to the deed, and the manner of it. I think you will have a letter from him soon. (Ltr. 63, Le Faye)

Although it appears Sir B read the newspaper rather than converse with Cassandra I think Jane is teasing her sister by suggesting she will receive an offer of marriage from Sir B by way of a letter. In the notes Le Faye says Sir B is Sir Brook Bridges, still a widower. In the biographical index it is listed that his wife Eleanor died in 1806. I suppose Jane might have continued to tease her sister until the gentleman remarried in 1809. (:D)