The met are loathed by all other forces including the city of london police
Yes your right those 4 ranks are indeed justices of the peace. Are more honestly, justices of inciting the plods to commit crimes against the citizenry under the pretext of keeping the peace.
Your bosses have some slogan, "policing by consent". Well there is no such think as policing by consent. There is only policing by act of parliament.