] Do you think thay used it to date the film to 1802, or simply used a near-date for atmosphere?

Without being psychic, it's impossible to give a firm answer, unless someone can come up with a report from the costume designer or whoever. However, my guess is that it was deliberate, simply because `The Porcupine' had such a limited run. If they were just providing atmosphere, then they could have had Mr Palmer reading a different paper. Besides, it's only historical anal-retentives like me who spot the reference.

Incidentally, our Military Intelligence Officer, Captain Everett, had something interesting to say about Col. Brandon's uniform in an earlier thread: follow this link.