you are correct . Although I have heard a few stories about coppers coming out to a firearm related incident and they did not know the laws themselves.
I had an Incident with an MOD police officer on my permission. He and his colleague were Armed ( they patrol a gas compressor installation) and he hit me with so much untrue crap I had to follow it up with the firearms office in Aberdeen .
He was spouting crap about me not carrying my FAC or even calling the police to say I was on the farm shooting .
He told me that if he looked me up on the PNC to see if I was legally holding firearms it would affect my renewal (it did not and never would affect it ).
He took a note of my serial number from my rifle (again he was not required to do so). He wanted to count all my ammunition (not required to do so ).
He told me that everything he did ,He was required to do so . The reply I got from the Firearms office was if he was to stop me again I was to call and ask for a armed response unit to come out and deal with it .That would use up a valuable resource in my eyes due to a ill informed or bully MOD policeman .
I carry a copy of the email I received along with a copy of all my licenses and permission slips in my bag .
The guy with him was a rookie so I guess he may be the same as that Diddy unless he then researched the RIGHT way to handle the situation.
I get stopped almost every time I visit the farm but i have never come across any that acted like that diddy .