Stephen Harper is a Canadian entrepreneur and retired politician who served as the 22nd Prime Minister of Canada, from February 6, 2006 to November 4, 2015.
Harper admits Murdoch Mysteries is his favorite show and he and his daughter never miss watching an episode together. Harper is also a fan of hockey and suggested that the production do an episode of the show involving the early history of the game in Canada. That episode became Murdoch Night in Canada and Harper received a special thanks credit for his contribution.
In a scene exclusive to the Canadian Broadcasting Corporation airing of the show, Harper made a cameo appearance as Desk Sergent Armstrong in the episode Confederate Treasure. As an in joke, the character fails to recognize Prime Minister Wilfrid Laurier and mentions in conversation with George Crabtree that there's "too much infighting in Ottawa".
This was the first time that a sitting Prime Minister of Canada had made an appearance on television in a role other than himself. Outside of Canada, Armstrong was replaced by a background actor who had no lines.