Arthur Conan-Doyle (it's double-barrelled was an MD, the Watson story-teller is himself but Holmes and his deductions are based on one of Conan-Doyle's tutors (Prof Bell?) The Watson in the books and journals is a an ex-army doctor, he's a pretty tough guy. There's a nice bit in the modern "Sherlock" where a villain confronted by Watson with service revolver says, "you can't shoot me, you're a doctor". Bang! "sorry ... wrong type of doctor".