I also had a bad experience with a large bloke hammering and banging on the door. The chain (well one of those latch thingies) was on and he could not enter so he was banging to door open and closed to try to break it.
There was an iron bar near the door so I picked it up and held it in striking position while shouting "you had better be <very naughty word here>ing ready for me pal".
I waited for the door to close before flicking off the latch knowing the force of him opening the door would make him stumble.
He did as I expected but, to my surprise, was wearing a police uniform so I decided not to welt him one.
I popped the bar on the floor and said, "good gracious, a policeman!".
He was after me for drugs offences. Turns out he had the right house but it was a pity he was on the wrong street.
Coppers go very red from time to time.