Sir David Thompson was the fist Roman Catholic Prime Minister. David Thompson was raised Methodist but converted to Catholicism a year after his marriage to Annie Affleck.
Following John A. Macdonald’s death in 1891, there was a cabinet crisis. Governor General Lord Stanley of Preston called on Thompson to form a government but Thompson declined. Religious prejudice against Thompson, made this course of action politically untenable, and Thompson recommended John Abbott, who ultimately accepted.