Three things make this episode almost worth seeing: the return of the gorgeous Bunty, the gorgeous red convertible driven by Bunty, and Sgt. Goodfellow being in charge for a change. The rest is tedious. Especially annoying is the character of Brenda; I'm not sure if the actress playing her was trying to be energetic, devilish, or retarded - she comes across as an extremely unappealing combination of all of these, and she's a major character in the episode.
The rest of the story is politically correct drivel. And while Goodfellow gets effusive compliments from Father Brown for his good work, it's actually Father Brown who solves the case (as usual), so the praise seems ingenuine. There's no Mallory, there's no Sid, no Mrs. McCarthy, the writing is poor; this seems like a budget episode. But they do have a nice car or two in it.