Before 1829, London did not have a unified police force committed to the investigation and prevention of crimes. Sure, they had constables, but their sole responsibility was to bring people accused of a felony to a justice of the peace for deliberation. This system may have served them well before the Industrial Revolution, but the surge in London's population meant a surge in crime, and the government needed to respond.
The Metropolitan Police Act of 1829 saw the creation of what is commonly known today as Scotland Yard, a unified police force that answered to the Home Secretary. An extra thousand officers were hired, in addition to the 400 officers already employed. They were given uniforms, and for the first time, police work was made a full-time job.
These new officers were derided by Londoners who saw the Metropolitan Police as an infringement on their personal lives - crime is a tough habit to break, it seems. The whole endeavour was a success, however, and crime rates dropped significantly in the ensuing years. Despite the odd bit of corruption, the coppers were tough and relentless in their aim to clean up the streets of London. Lovely news for Jacob Frye and the Rooks, isn't it?