Service Police

In the United Kingdom, the term military police refers to the three branches of the service police. Often, the term 'military police' is considered synonymous with the Royal Military Police, but in fact, has a wider context. There are a number of civilian police forces whose role is to police other parts of the Defence Estate in the UK and overseas, but such forces are not correctly referred to as military police.

In the UK, service police are the formations of the British Armed Forces responsible for policing armed forces personnel. They are comparable to the provosts of other countries, however the term provost in the UK has various uses including reference to the staff of military prisons and senior service police officers (e.g. the Provost Marshal). Each of the services has its own service police branch, a standalone unit responsible for policing, close protection of VIPs and, in the case of the Royal Military Police and Royal Air Force Police, other matters such as traffic control.

Service police are not constables under UK law and do not have any constabulary powers over the general public, however they have the full range of policing power that constables possess when dealing service personnel or Civilians subject to Service Law. However, the service police can utilise the powers, available to all persons in England and Wales, under Section 24(A) of the Police and Criminal Evidence Act 1984; which allows any person to arrest any individual they have reasonable grounds to believe is committing, or has committed, an indictable offence, and that a constable is not available to perform the arrest. They are allowed to use such force as is reasonable in the circumstance to achieve this. A similar power of arrest exists under Scottish common law, but there is a requirement to use the minimum amount of force and for the Military Police officer to have directly witnessed the individual commit the act for which they are arresting them.

...
Wikipedia