The Royal Navy Police (RNP), or Royal Naval Police, formerly known as the Royal Navy Regulating Branch, is the military police branch of the British Royal Navy. Its members are known as Regulators and enforce law, order and discipline both aboard ship and in shore establishments. Unlike the Royal Military Police and Royal Air Force Police, the Regulating Branch only recruits from personnel who are already in the Navy and have a minimum of four years' service in another trade. Its members hold a minimum rate of Leading Regulator (Leading Rating) and can be promoted to Regulating Petty Officer (Petty Officer), Master-at-Arms (Chief Petty Officer) and Warrant Officer Master-at-Arms Class 1. Unlike the majority of the Royal Navy, Warrant Officer Class 2 is not an attainable rank within the RNP.
The Regulating Branch has its own Special Investigation Branch (SIB), which is employed investigating serious crimes. The trade badge for Regulators is a crown (worn in a wreath by Masters-at-Arms and Warrant Officer Masters-At-Arms). Non-police Officers attached to the Royal Navy Police wear a white armlet on the left wrist bearing a crown between the letters "NP" (Naval Patrol).
Among the rest of the Navy, Regulators are held in a certain amount of suspicion for leaving their initial trade. They are also known for their almost universal virulent insistence on being addressed by their branch-specific titles ("Leading Reg", "RPO" or "Master" depending on rate), thus emphasising their position of authority.
Nicknamed "Crushers", it is the Regulators who punish other personnel for rules infractions (including such things as returning to the ship late or drunk), administer compulsory drug testing, and conduct criminal investigations. As one would imagine, this does little to endear them to the rest of the Navy, despite the essential nature of these jobs.
In addition to their law enforcement role, Regulators aboard warships serve a more utilitarian function, these include being a member of the ship's hangar crew and manning the ship's helm. Plus they over see the Shore patrol.
The RNP will also absorb the Royal Marines Police.
RN Police are now trained at the Defence Police College, Southwick Park, along with the Royal Military Police and Royal Air Force Police.

Surface Fleet
Fleet Air Arm
Submarine Service
Royal Navy Regulating Branch
Royal Naval Reserve
Queen Alexandra's Royal Naval Nursing Service
(includes Royal Marines Reserve)