 It has been illegal for police officers to work part-time as security guards in the United Kingdom since 1934.There are ten companies whose employees are sworn in as constables under section 79 of the Harbours, Docks, and Piers Clauses Act 1847.As a result, they have the full powers of a constable on any land owned by the harbour, dock, or port and at any place within one mile of any owned land.