I saw Alec Guinness play Father Brown in the film version some years ago and an enjoyable film it was as well. It was a shame he did not make more Father Brown films.
This television adaptation by the BBC, shown in the afternoons might not be for the purists who have read the books and appalled at the changes made.
The TV adaptation because of budgetary reasons require a fixed location (such as the village setting) fixed sets and a small regular cast of characters as the core actors have to be retained for the duration of the shoot.
The period setting has moved forward to the 1950s, a time of post war change and Father Brown might be deemed to be a little too modern with some liberal sensibilities. Then again he is a man who has himself experienced the horrors of war and we believe has travelled widely and open to new experiences even though he is a Catholic priest.
The murder mysteries are enjoyable, easy viewing for the whole family. Some of the stories in the TV series are new and others are based on the books by Chesterton.
In the books, Father Brown might be deemed to a be a peripheral character, somewhat on the edge. In one of the stories I did read and which the series did adapt (The Blue Cross,) it was noticeable how pacey and thrilling the adaptation was in contrast with the book.