don't want him as an enemy, i would have laughed, sorry, but i respect the law, and i respect police officers, well the good ones anyway, i have several mates in the force and the majority of coppers are decent. but at the end of the day he is just a person.
i would have stopped him and asked him for his name and badge number, and also who his C O is and i would have told him i would be reporting him and also expalining to his C O that elle muppet was using threating behaviour when no law had been broken.
as long as your polite and are not threating back there is bugger all he can do, he can't pull you for anything and he can't charge you with anything.