Getting into work mode

Also reading Georgette Heyer. She is delightful. But very very very hard to understand. Why does she use so much 1820s slang? Even books actually written in the 1820s aren't written like this. It actually makes the book very difficult to read, much more so, at least for me, than something like Dickens or Proust. Example:

He was quite a pretty whip, but n…