the control of the Home Secretary. Initially, the government proposed to retain the areas outside the local government boundary, with a representative appointed to the Metropolitan Police Authority from the councils outside the Greater London Authority boundary. However the government changed its mind and in the Greater London Authority Act 1999 the boundaries of the Metropolitan Police District were redefined to match Greater London. The excised county areas were reassigned to Essex Police, Hertfordshire Constabulary and Surrey Police. Use for other purposes The London Coal and Wine Duties Continuance Act 1861 aligned the coal tax boundary to the MPD and a series of coal-tax posts can be found along the boundary as it existed at that time. During the 20th century the population of the County of London was in decline and the London population was growing in the outer suburbs within the MPD. During this period the MPD was used as a definition of 'Greater London'. 1901 Census is an example of this. Exceptions Not all parts of Greater London, although within the boundaries of the MPD, are policed by the Metropolitan Police. The Greater London Authority Act 1999 defines the Metropolitan Police District as consisting of "Greater London, excluding the City of London, the Inner Temple and the Middle Temple." The City of London has its own police force, the City of London Police, which also covers the Inner and Middle Temples. As constables of both forces are empowered throughout England and Wales, mutual assistance is a routine matter. The City of London has limited policing jurisdiction with parks constabularies within their lands at Hampstead Heath and Epping Forest (constables are attested under the Greater London Parks & Open Spaces Act 1967 and the Epping Forest Act 1878 respectively not under the Police Acts as members of the City of London Police). The London Underground and the lines and stations of the national railway network within the MPD are primarily policed by the British Transport Police but are not excluded from the jurisdiction of the Metropolitan Police. The Royal Parks of London used to be policed by the Royal Parks Constabulary (RPC) whose powers derived from the Parks Regulation Act 1872. The Serious Organised Crime and Police Act 2005 abolished the RPC in England and Wales and provided for the transfer of personnel within Greater London into the Metropolitan Police, leaving the Royal Parks within the general jurisdiction