He was born in Napanee, Canada West, the son of John Thomson and Annie Oswald, both natives of Ireland, and was educated in Uxbridge. In 1877, Thomson married Maggie Walden. He served as reeve and then mayor of Owen Sound. Thomson was elected to the House of Commons in a 1903 by-election held after the death of Edward Henry Horsey.[2] He was defeated when he ran for reelection in 1904.[1]