In the Norton Critical Edition, there is a small note about the opposition, which reads as follows:

The party not in power at the moment. Assuming thatthe action takes place not long after 1805, Willoughby might be a Foxite Whig, and Mr.Palmer was certainly a Tory. Local politics were often vehement enough to precude socializing between members of opposing parties.

'Foxite' would be named after Charles Fox, who was a prominent figure of the time.

The Palmers made a seemingly whirlwind and surprise trip to Barton, and it was at Mr. Palmer's instigation. Since he evidently does not particularly care for his in-laws, I've been wondering if his trip might have something to do with his campaigning to be a Member of Parliament (M.P.).? Perhaps he needed something from Sir John? (Although I can't imagine what!) Charlotte didn't even know they were going to Barton until the carriage was at the door, and then stayed only a very short while.