From Wikipedia

History Of The British Police Service

The history of law enforcement in the United Kingdom charts the development of law enforcement in the United Kingdom from the creation of the United Kingdom in 1707 up to the present day.
With the notable exception of the famous Bow Street Runners, established in 1792 under the Middlesex Justices Act 1792, virtually all the fledgling police forces were established by attesting special constables, a procedure conducted by two or more Justices of the Peace and having its roots in an Act of Parliament of 1673. Further Acts of Parliament started to appear piecemeal, sponsored by local members of parliament and Peers who represented certain social or industrial interest groups (for example, Metropolitan Police Act 1829, and the Bute Docks Police Act 1839). It was not until 1847, when two significant pieces of legislation were enacted - the Town Police Clauses Act 1847 (in the case of town police) and the Harbours, Docks, and Piers Clauses Act 1847 (in the case of port police) - that national legislation appeared to support the widespread attestation of professional constables.