I discovered a classic BBC mystery series that I’ve grown quite fond of. It definitely has the feel of a Lord Peter Wimsey or Agatha Christie, which I believe are both also set in the 1920’s.
It’s based on a series of short stories by G. K. Chesterton. I can’t personally vouch for how faithful it is to the books, but knowing old-school BBC adaptations, it’s probably very close.
The main character, Father John Brown, is a Catholic priest who (surprise, surprise) also is an amateur sleuth. His faith plays a prominent role in his detective work.
I believe there’s a new series based on the same short stories. I can’t imagine it could be as good as these, but I’m withholding all judgment until I’ve seen both.