For some reason, the writer(s) changed the working formula of their usual, lighthearted, fun-to-watch episodes into a heavy, dark episode that was not fun to watch.
Whether it was a different set of writers or just to try to gain viewership, I can't tell, but this isn't the Father Brown I have enjoyed for 9.9 seasons.
Bad writing, giant plot holes, asinine and needlessly vitriolic characters all made for an unenjoyable episode. Where in previous episodes, Father Brown plays a major role, with a lighthearted, intelligent acumen, in this episode, he's been given a smaller, almost useless role.
I hope this isn't going to be the norm in season 11... otherwise this is another series I'll have to jettison.