The Office of Constable

Every sworn police officer in England and Wales is a ‘Constable’, irrespective of rank. It is from the Office of Constable that each officer derives their powers. 

On appointment each police officer makes a declaration to "faithfully discharge the duties of the Office of Constable". In England and Wales, police officers swear an oath of allegiance to the monarch; this is to ensure the separation of power and the political independence of the Office of Constable. 

The Office of Constable means a police officer has the additional legal powers of arrest and control of the public given to him or her directly by a sworn oath and warrant. These are not delegated powers simply because they have been employed as an officer. Police officers are not employees. 

Each sworn constable is an independent legal official; they are not agents of the police force, police authority or government. Each police officer has personal liability for their actions or inactions. The chief officer of the force to which the constable is attached also has a level of corporate responsibility.

The Office of Constable (polfed.org)