Just caught probably the earliest ever reference to Mrs. Clam from the Sister Boniface Mysteries in my Father Brown rewatch.
We never see this character, but discussing the investigation with Inspector Mallory in S06e06, Mrs. McCarthy mentions a "Vera Clam" who works at the post office and is the "most terrible gossip."--all of which correspond directly with the character that we later see in the spinoff show.
So I like to think that Vera Clam got tired of all the murders that happened in Kembleford and eventually moved to Great Slaughter--only to find that murders happen nearly as frequently there and this time, she herself will have to assist with solving them.











