Damsel in Distress by P.G. Wodehouse
I thoroughly enjoyed this hilarious tale of mistaken identity, thwarted romances and upstairs/downstairs interactions that takes place in the early 19th century. If you like Wodehouse's Wooster and Jeeves or Blandings Castle novels, you will enjoy this stand alone story. If you are enjoying Downton Abbey, this would be a lighthearted take on the same period.
I read it on my Kindle, but the library has an audio version that you can check out, which is very well read by Jonathan Cecil. It was later made into a movie starring Fred Astaire.