"It is my belief, Watson, founded upon my experience, that the lowest and vilest alleys in London do not present a more dreadful record of sin than does the smiling and beautiful countryside."William Bolitho, in a passage that I love, called Holmes "the spirit of a town and a time." The town, of course, is London. And yet it is astonishing how many of his adventures take him outside of London proper and into the countryside. Sometimes that countryside is a bedroom community of London, sometimes farther afield.
-- Sherlock Holmes, "The Adventure of the Copper Beaches"
It would be tedious to list examples, but almost half of the tales in The Adventures of Sherlock Holmes -- five out of twelve -- take Holmes out of the city down country lanes for at least part of the story. So do half of book-length adventures -- The Hound of the Baskervilles and The Valley of Fear. (I don't know about The Sign of Four. Pondicherry Lodge is not in the city, but I'm not sure it would be considered country, either.)
Maybe Sherlock Holmes wore that style of country cap called a deerstalker more often than we Holmes fans generally believe. What do you think?