The Underground Electric Railways Company of London, Limited (UERL), known operationally as the Underground for much of its existence, was established in 1902. It was the holding company for the three deep-level "tube"[note 1] underground railway lines opened in London during 1906 and 1907: the Baker Street and Waterloo Railway, the Charing Cross, Euston and Hampstead Railway and the Great Northern, Piccadilly and Brompton Railway. It was also the parent company from 1902 of the District Railway, which it electrified between 1903 and 1905. The UERL is a precursor of today's London Underground; its three tube lines form the central sections of today's Bakerloo, Northern and Piccadilly lines.
The UERL struggled financially in the first years after the opening of its lines and narrowly avoided bankruptcy in 1908 by restructuring its debt. A policy of expansion by acquisition was followed before World War I, so the company operated most of the underground railway lines in and around London. It also controlled large bus and tram fleets, the profits from which subsidised the financially weaker railways. After the war, railway extensions took the UERL's services out into suburban areas to stimulate additional passenger numbers so that, by the early 1930s, the company's lines stretched beyond the County of London and served destinations in Middlesex, Essex, Hertfordshire and Surrey.
In the 1920s, competition from small unregulated bus operators reduced the profitability of the road transport operations, leading the UERL's directors to seek government regulation. This led to the establishment of the London Passenger Transport Board in 1933, which absorbed the UERL and all of the independent and municipally operated railway, bus, and tram services in the London area.
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