If somebody has been given a police caution for a crime and the police officer dealing with the crime told you to get to the nearest hill and run as far as you can with regards to this person - can the person that called the police in the first place still press charges 2 weeks after the event?
You're in luck Dutty_Burd. There was an appeal case not three weeks ago in the House of Lords called
LAWRENCE JOHN JONES v STEPHAN JOSEPH WHALLEY (2006)
The thrust of the case was that someone had agreed to a caution and, on that basis, there would be no Crown Court prosecution. A subsequent private prosecution then failed because it would have been an "abuse of process".