The Police Officer as Sidekick: Sam Gillepsie

The police officer as assistant to the "great detective" is a common trope in mysteries. Sometimes, the officer is wry and sarcastic, like the excellent Rupert Graves as Lestrade in Sherlock.

Sometimes, the officer is short-tempered and belligerent as several officers with Father Brown.

Sometimes, as in Jeremy Brett's Return of Sherlock Holmes, the sidekick, Lestrade, is hopeful and complimentary. The end of "The Six Napoleons" presents a wonderful speech by Colin Jeavons as Lestrade:

Inspector Lestrade: I've seen you handle a good many cases in my time, but I don't know that I ever knew a more workmanlike one than this. We're not jealous of you, you know, at Scotland Yard. No, sir, we're proud of you. And if you come down tomorrow, there's not a man from the oldest inspector to the youngest constable... who wouldn't be glad to shake you by the hand.  

Max Brown as Sam Gillepsie from Sister Boniface is a nice addition for multiple reasons. Most importantly, he isn't at odds with the good sister. He happily accepts her assistance. (Marshal Cecchina from Don Matteo shares the same trait and upbeat relationship with the "interfering" religious detective.) 

Mrs. Clam initially says, "Couldn't I just say, 'Help'?"

In fact, based on his welcome of Felix, Sam is a man set on establishing a safe family/group of comrades for himself in his village. 

He doesn't come across as stupid--as sometimes  sidekicks do--but rather as invested and action-oriented, when required. His exemplary war record heavily implies that here is a man who has learned the value, in peace time, of his "live and let live" side. He wants an orderly village because he loves it and wants the people around him to be happy, not because he is devoted to legal outcomes. 

Lorna Watson as Sister Boniface is, naturally, brilliant as the clever, whimsical, practical, sweet-natured, and ever so slightly innocent Great Detective.