Sir Robert Peel is commonly known as the father of modern policing. He is famous for two main contributions to policing. Those contributions are the creation of a unified police force that acted as public servants and the institution of police patrols for crime prevention.
Although some scholars say that reforms were underway to some degree before Peel, Peel is generally credited with having created a new type of policing. Before Peel, policing in the London metropolitan area was organized by parish. Each small area of the city was supposed to provide its own constables. This led to poor organization on the metropolitan level. It also led to a situation in which many constables took their offices in order to make money through corrupt means. Before Peel, then, policing was fragmented, disorganized, and often corrupt. To reform the system, Peel introduced the Metropolitan Police Act of 1829. This act centralized control of the police force, solving the organizational problem. It also made the police into public servants, rather than free agents working for themselves. This was a very important step in the history of policing.
Before Peel, the police forces were much more reactive and much less proactive. They were more likely to respond to crimes and to try to apprehend criminals than to prevent crimes. Peel instituted a system of organized police patrols. These patrols were meant to prevent crime from happening in the first place through a regular police presence. This was very important in that it changed the main role of the police.
For these reasons, Sir Robert Peel is typically seen as the father of modern policing.