John Stuart Buchan was born on October 28, 1852, in St. Andrews, Argenteuil, Quebec.

In 1864, he graduated from McGill University Law School and became a member of the law firm Taylor and Buchan (1864-1927). In 1894, he was elected President of the Baptist Convention of Ontario and Quebec. He was also an author who wrote the novel "A Bit of Atlantis" (1900) under the pseudonym Douglas Erskine.

In 1885, he married Catherine Jane McMartin (1853–1894). In 1896, he remarried Annie Henderson (1859–1911). He died on February 10, 1927, in Verdun, Quebec.