If you're ever unlucky enough to be in that situation DON'T ACCEPT A POLICE CAUTION. You might as well paint a sign that reads 'Criminal' and hang it round your neck. And start advertising your guns, because you won't be using them any more.
Here's an excerpt from PC Bloggs, a blog written by a cynical (and anonymous) police officer, which explains a bit more:
NCRS has meant that we can no longer attend a crime and write it off with the words "advice has been given to all parties". * If there is a suspect, for any offence no matter how minuscule, we are expected to arrest them, log their fingerprints and DNA, and "dispose" of them in such a manner that it causes a detection for the superintendent's monthly figures. Many adults unused to the criminal justice system believe that if they cooperate, everything will be all right. In fact if they cooperate they receive a Caution, supposedly a warning that drops straight off your record and has no effect on your life.
Wrong. A police caution can and will stop you getting jobs, travelling abroad or being involved with children. Even a common assault where you've had a scuffle with your adult brother can preclude you from a job as a teacher, police officer, or even taxi driver.
The result, the criminalisation of a vast tract of society who should never have seen the inside of a police cell. While the real crooks play the system with their entourage of Mr and Mrs Loopholes, and walk out laughing.