Old bill in doing their job shocker

This, like the idea that you are meant to help the police (or meant to do anything), needs a context to make any sense - you would need to add in who means you to help the police, why you should be helpful and so on, without this context it appears to be simple unthinking obedience.

Sorry, i mean society, conscience, middle class values etc.

Tynan, if you see an old lady drop her purse and not notice, do you need someone to tell you to pick it up and give it her back? Or do you just do it?
I'm sure you know what I'm getting at and are just playing devils advocate.

In the OP, what would have happened if he'd said " I'm not telling you anything unless you arrest me."
I understand how this infringes on 'innocent until proven guilty' but the police would be a whole lot more inneffective if no one cooperated with them at all.