In the 1700s the crime victims had to go to the magistrate, who then sent a policeman known as a constable to look for the criminal. In the newspapers there were adverts of wanted criminals as well as rewards. But this system of rewards was exploted by thief-takers, who were men that worked capturing criminals.

The thief-takers were often criminals, who blackmailed other criminals. This worried the magistrates, so they employed thief-takers as "runners" working together in the capture of criminals.This innovations formed in 1829 the modern police of london.