was given priority over the maintenance of the Underground. In 1953 an unpainted aluminium train entered service on the District line, and this became the standard for new trains. In the early 1960s the Metropolitan line was electrified as far as Amersham, and steam locomotives no longer hauled passenger trains. The Victoria line, a new tube line across central London, opened in 1968–71 with trains driven automatically. In 1976 the isolated Northern City Line was taken over by British Rail and linked up with the mainline railway at Finsbury Park. In 1979 another new route, the Jubilee line, took over part of the Bakerloo line; it was extended through the Docklands to Stratford in 1999. Under the control of the Greater London Council, London Transport introduced in 1981 a system of fare zones for buses and underground trains that cut the average fare. Fares increased following a legal challenge but the fare zones were retained, and in the mid-1980s the Travelcard and the Capitalcard were introduced. In the early years of the 21st century, London Underground was reorganised in a public–private partnership where private companies upgraded and maintained the infrastructure. In 2003 control passed to Transport for London (TfL), which had been opposed to the arrangement and, following financial failure of the infrastructure companies, had taken full responsibility by 2010. The contactless Oyster card first went on sale in 2003. The East London line closed in 2007 to be converted into a London Overground line, and in December 2009 the Circle line changed from serving a closed loop around the centre of London to a spiral also serving Hammersmith. Currently there is an upgrade programme to increase capacity on several Underground lines, and work concluded in 2021 on a Northern line extension to Battersea. The first underground railways (1863–1905) In the first half of the 19th century, London had grown greatly and the development of a commuting population arriving by train each day led to traffic congestion with carts, cabs and omnibuses filling the roads. By 1850 there were seven railway termini located around the urban centre of London and the concept of an underground railway linking the City of London with these stations was first proposed in the 1830s. Charles Pearson, Solicitor to the City of London, was a leading promoter of several schemes, and he contributed to the creation of the City Terminus Company to build such a