This is an interesting word that Dr Watson uses to describe the country police sergeant who aids in solving the mystery of The Vally of Fear, one of The Greatest Adventures of Sherlock Holmes. I’ve never heard this word, and from the context, I thought it meant something different, so I’m glad I looked it up.
Bucolic – pertaining to or suggesting an idyllic rural life
Usage: “But, I say,” remarked the police sergeant, whose slow, bucolic common sense was still pondering the open window.