Be My Guest

I was engrossed in an 1840s’ period drama, and my language detectors suddenly kicked into gear when one of the characters said “be my guest”. To me, the phrase sounded too modern for the time, and on looking into it, I found that it was. “Be my guest”, meaning “You’re welcome (to something); do as you please (OED)” had its first recorded usage in 1955, so well over a century after the 1840s. Oops!