|Mentioned|| "Evil Eye of Egypt"|
"Stroll on the Wild Side (Part 1)"
Armstrong is a Constable at Station House Four.
Armstrong appears in only one episode, "Confederate Treasure", portrayed by then Canadian Prime Minister Stephen Harper in a cameo appearance. Although Armstrong has not appeared since, other characters will regularly refer to him as a recurring joke. For example, in "Evil Eye of Egypt", Armstrong reports hearing a suspect speaking conspiratorially, causing Murdoch to remark that "Armstrong hears conspiracies around every corner." In "Stroll on the Wild Side (Part 1)", Armstrong is a said to be on leave and unable to pitch in Station House Four's baseball game against Station House Five, though Brackenreid remarks that last year was a "debacle", and he wouldn't be pitching anyway.
Armstrong only appears in the Canadian airing of "Confederate Treasure". When the episode aired on Alibi in the United Kingdom, he was replaced by the station's regular desk clerk.
- Armstrong predicts that Ottawa HC will not win the Stanley Cup as there is "too much infighting in Ottawa", referencing Ottawa's role as the capital of Canada, and site of disputes between politicians such as Harper.
- In a similar joke, Armstrong fails to recognize Prime Minister Sir Wilfred Laurier when he walks into the station.