I know this story is in the UK, but at least in the US you absolutely should assume they will not help, and depending on the circumstances will make the situation even worse. They have no duty to do anything to help, and no consequences if they don't.
> "Masked guy repeatedly visits at night to write threatening messages on car of single woman living alone" is... about as explicit as you can get.
Or alternatively its an invitation for a police officer or a department to suddenly need to do a lot of work that they could just...not do. No skin off their back if someone is being harassed or stalked, and if something worse happens, they can investigate then. Why spend the resources now after all?
> "Masked guy repeatedly visits at night to write threatening messages on car of single woman living alone" is... about as explicit as you can get.
Or alternatively its an invitation for a police officer or a department to suddenly need to do a lot of work that they could just...not do. No skin off their back if someone is being harassed or stalked, and if something worse happens, they can investigate then. Why spend the resources now after all?