Page "London Underground" Paragraph 2

The earlier lines of the present London Underground network were built by various private companies.

They became part of an integrated transport system in 1933 when the London Passenger Transport Board ( LPTB ) or London Transport was created.

The underground network became a separate entity in 1985, when the UK Government created London Underground Limited ( LUL ).

Since 2003 LUL has been a wholly owned subsidiary of Transport for London ( TfL ), the statutory corporation responsible for most aspects of the transport system in Greater London, which is run by a board and a commissioner appointed by the Mayor of London.