Buch·an 
(bŭkən, bŭ-), Sir John First Baron Tweedsmuir. 1875-1940.
(bŭkən, bŭ-), Sir John First Baron Tweedsmuir. 1875-1940. British writer and government official who was governor-general of Canada (1935-1940) but is best known for his adventure novels, such as The Thirty-Nine Steps (1915).