Brompton & Piccadilly Circus Railway

The Great Northern, Piccadilly and Brompton Railway (GNP&BR), also known as the Piccadilly tube, was a railway company established in 1902 that constructed a deep-level underground "tube" railway in London.[note 1] The GNP&BR was formed through a merger of two older companies, the Brompton and Piccadilly Circus Railway (B&PCR) and the Great Northern and Strand Railway (GN&SR). It also incorporated part of a tube route planned by a third company, the Metropolitan District Railway (MDR). The combined company was a subsidiary of the Underground Electric Railways Company of London (UERL).

More information on the Wikipedia page.

See also Piccadilly Line.