Conservator of the peace
In ancient British customs, Conservators of the Peace (Latin: Custodes pacis), or Wardens of the Peace, were individuals who had a special charge, by virtue of their office, to see that the King's peace was kept.
Until the creation of the Justices of the Peace by King Edward III, there were several people, who by common law were interested in keeping the same—some having that charge as incident to other offices; others simply, or of itself, called custodes, or Conservators of the Peace.
More recently, the Chamberlain of Chester was a Conservator in the county of Cheshire; and petty constables are, by the common law, conservators in the first sense.
The Conservator of the Peace title is still used in the USA. For example, in Virginia, Special Conservators of the Peace upon a showing by the applicant of a necessity for the security of property or the peace and presentation of evidence that the person or persons to be appointed as a special conservator of the peace possess a valid registration issued by the Department of Criminal Justice Services. The order of appointment shall provide that a special conservator of the peace may perform only the duties for which he is qualified by training as established by the Criminal Justice Services Board. The order of appointment shall provide that such duties shall be exercised only within geographical limitations specified by the court, which shall be within the confines of the county, city or town that makes application or on the real property where the corporate applicant is located, or any real property contiguous to such real property. The order may provide that the special conservator of the peace shall have the authority to make an arrest outside of such geographical limitations if the arrest results from a close pursuit that was initiated when the special conservator of the peace was within the confines of the area wherein he has been authorized to have the powers and authority of a special conservator of the peace; the order shall further delineate a geographical limitation or distance beyond which the special conservator of the peace may not effectuate such an arrest that follows from a close pursuit. The order may also provide that a special conservator of the peace who has completed the minimum training standards established by the Criminal Justice Services Board, has the authority to affect arrests, using up to the same amount of force as would be allowed to a law-enforcement officer employed by the Commonwealth or any of its political subdivisions when making a lawful arrest. No special conservator of the peace shall display or use the word "police" on any uniform, badge, credential, or vehicle in the performance of his duties as a special conservator of the peace. Other than special conservators of the peace employed by a state agency, no special conservator of the peace shall use the seal of the Commonwealth on any uniform, badge, credential, or vehicle in the performance of his duties.
References
https://law.lis.virginia.gov/vacode/title19.2/chapter2/section19.2-13/
