When an exceptional London policeman discover a cult of murderers in a remote English village, he and his clumsy partner must bring them to justice.

When an over-achiever cop is involuntarily transferred from a crime riddled city to a crime free village, he must convince the locals that a series of accidents are actually murders.

When an over-achiever cop is involuntarily transferred from a crime riddled city to a crime free village, he must convince the locals that a series of accidents are actually murders.

Hello, I think you should keep it one sentence long. I suggest you to use the usual logline formula:

When [inciting incident] happens, [adjective]+[hero] must do [action] and fight [opponents] to reach [goal].

The trick is to focus only on the most importants elements. For exemple, there is no interest in the nale of the town "stanford", it's just a small town. It would be better not to mention "london" because the movie would be the same with any big city, in this case maybe ou can use because the movie is already done.

Try to keep in mind the irony of the movie: an uptight super cop in a dead calm small town... apparently!

What is the hero's goal? To catch a swan? Yes but NO, this is just an assignment, the real goal is as you said 'to bring justice'. Now you have to build one sentence which starts with the inciting event and goes to the hero's goal. Between the incident and the goal there is CONFLICT.