I remember that in Flame-Colored Taffeta! Gosh, I found that SO jarring, although I'm sure Sutcliff had some source or other that showed someone from the time doing just that. In some ways it's easier when writing historical fiction about people speaking something other than English, because you can "translate" (as it were) into something that won't jar modern speakers, instead of going, well, in the 1750s people used the word lover this way! ...as the modern reader blinks and goes "What?"