After graduation, Sproule first practised medicine at Craighurst, Ontario before moving to Galesburg, Michigan. He moved back to Grey County, settling in Markdale, Ontario, where in addition to his medical practice, he also opened a drug store, bought a large cattle farm, and invested in local businesses such as a flour mill and lumber yard. He turned to politics and succeeded the retiring William Kingston Flesher as MP of Grey East in the 1878 election as a Conservative MP. He also fell in love with Flesher's daughter, Mary Alice, and wooed her by having a beautiful Italianate house that he called Knarsboro Hall built for her in Markdale. The couple was married in 1881, and had a daughter, Lillian. T.S. Sproule was also related to the famous NHL Toronto St. Patricks owner Harvey Sproule. T.S. Sproule's niece was Mary Elizabeth Sproule Head, of Milton, Ontario, who along with her husband John Head, cared for her young nephew Harvey Sproule and his sister. Sproule was subsequently re-elected to Parliament eight times in succession. Both Sproule and his wife were dedicated teetotallers and Prohibitionists, and when Mary Alice Sproule was the hostess of her husband's political functions, she never allowed alcohol to be served.
Political views
Sproule was a staunch Protestant from an Irish Unionist background. He was a member of the Orange Order, and rose to the position of "Master and Sovereign". In 1906, he became "President of the Imperial Grand Council of the World". The Order was noted for its anti-French and anti-Catholic views, particularly in that period. As a Conservative MP, he was a supporter of Prime Minister Sir John A. Macdonald, but his loyalty to Orangeism led him to differ with his party's leadership on issues of language and religion, particularly on the Manitoba Schools Question. Sproule opposed any concession to Catholic Separate Schools or French language instruction. Following the fall of the Conservative government in the 1896 election, largely due to divisions over the school issue, he became a pronounced critic of the immigration policies of Sir Wilfrid Laurier's government. Sproule opposed the admission to Canada of non-British migrants. He supported the abolition of French language instruction in Ontario schools, and the implementation of Regulation 17. Sproule also opposed the expansion of French language services by the federal government.
Following the defeat of the Laurier government in the 1911 election, the new Conservative Prime Minister, Robert Laird Borden, nominated Sproule to the position of Speaker of the House of Commons. Because Sproule had to lead the House in prayers in both English and French, he embarked on French lessons despite being a lifelong opponent of the language. During a thirty-six-day filibuster on the question of the government's naval bill, Sproule lost his patience after weeks of 24-hour sessions, and became the first Speaker ever to "name" a member of the House for disorderly conduct.
Illness and death
Sproule was forced to retire from the Speakership due to ill health, and was named to the Senate of Canada in 1915. He served for two years until his death in 1917. Four years after his death, Sproule's wife Mary Alice sold Knarsboro Hall, the house Sproule had built for her, and went to live with her daughter where she stayed until her death in 1941.
