Miscellaneous Constabularies
These constabularies generally come under the control of a local authority, public trusts or even private companies; examples include some ports police and the Mersey Tunnels Police. They could have been established by individual Acts of Parliament or under Common Law powers. Jurisdiction is generally limited to the relevant area of private property alone and in some cases (e.g. docks and harbours) the surrounding area. This, together with the small size of the constabularies, means they are often reliant on the territorial force for the area under whose jurisdiction they fall to assist with any serious matter. The statutory responsibility for law and order sits with the territorial police forces even if there is a specialist police force in the locality. These constabularies do not have independent Police Authorities and their founding statutes (if any) do not generally prescribe their structure and formation.
Read more about this topic: List Of Law Enforcement Agencies In The United Kingdom