Nothing wrong with "Plod", as a collective term.
I've heard the force called really unpleasant things, not used those terms myself but they are commonly used.
"Plod", comes from Noddy stories. You can't get more benign than that.
Makes me laugh that you had an official 'lay visitor', inspecting position, LR. How were you chosen?
Owl: "...he condemns all coppers but will bleat "please Mr Policeman, help me" when he's burgled or robbed."
Nobody is condemning all coppers! They are not above scrutiny though. You are too sensitive about them because your son is a police officer.
Yes we'd all call the police if we were robbed, then wait five hours for a junior officer to turn up who does nothing.