Port of London Police

The Port of London Authority (PLA) is a self-funding public trust established by the Port of London Act 1908 to govern the Port of London. Its responsibility extends over the Tideway of the River Thames and its continuation (the Kent/Essex strait). It maintains and supervises navigation, and protects the river's environment.

The PLA originally operated all enclosed dock systems on the river (except the Regent's Canal Dock), but these have long been closed to commercial traffic, with the exception of Port of Tilbury, which was privatised in 1992.

The PLA's responsibility extends from a point marked by an obelisk just downstream of Teddington Lock (the upstream limit of the tidal river) to the end of the Kent/Essex strait of the North Sea (between Margate to the south and Gunfleet Lighthouse, near Frinton-on-Sea, to the north,) a total of about 95 miles (150 km). The PLA does not cover the Medway or the Swale.

From the City of London, via the Thames Conservancy, the PLA inherited the conservancy, management and control of the river instead of ownership of the bed of the river and foreshore (the Crown was prohibited from alienating any of its lands by section 5 of the Crown Lands Act 1702, the Crown was presumed to own the bed of Thames and 'as conservators' the City of London were prohibited from owning any part of that same river bed) from Teddington to the Yantlet Line (between Southend and Grain).

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