<P> In May 2011 Johnson raised the issue with the President of the United States, Barack Obama, who was fined £ 120 after driving through London in the Presidential state car without paying the toll during a state visit to Buckingham Palace . The United States subsequently claimed diplomatic immunity . A TfL spokesperson noted that U.S. embassies do pay tolls in Oslo and Singapore . As of December 2013, Transport for London estimated that £ 82m was owed by foreign embassies in London . Since the charge was introduced in 2003, the U.S. Embassy owes the most with £ 8.78 million, followed by Japan at £ 6.0 million, Russia with £ 5.22 million and Nigeria with £ 4.92 million . </P> <P> The government's Smeed Report of 1964 was the first full assessment of the practicality of road pricing in a British city on the basis of congestion . It recommended a method of "car user restraint" by a variable system of charging for road usage--if the government had the will to do so . During the early years of the Greater London Council, which was formed in 1965, the first plans were drawn up for a system of cordon charging or supplementary licensing for use in the central area . A formal study was undertaken into the merits of the scheme, and in 1973 concluded that it would improve traffic and environmental conditions in the centre . These plans were being developed at the same time as the London Ringways, a series of 4 orbital motorways around and within London including Ringway 1 (the London Motorway Box) leading to widespread public protest by Homes before Roads and others . Only a small section of these road schemes had been implemented by the time Labour gained control in the 1973 Greater London Council elections, and the new administration abandoned the road building plans in favour of public transport and traffic management . The new administration, to which Ken Livingstone had just been elected for the first time, studied a congestion scheme similar to the one which was eventually adopted the following year . </P> <P> In 1995, the London Congestion Research Programme concluded that the city's economy would benefit from a congestion charge scheme, the Road Traffic Reduction Act 1997 required local authorities to study and reduce traffic volumes and any future London mayors were given the power to introduce "Road user charging" by the Greater London Authority Act 1999 . In his manifesto for the 2000 London Mayoral election, Ken Livingstone had proposed to introduce a £ 5 charge for vehicles entering central London . </P> <P> Following his victory, the Mayor made a draft order and requested a report from TfL, which summarised the reasons for introducing the scheme . The scheme was to be introduced to reduce congestion in the centre of the capital following the Draft Transport Strategy of January 2001 which had highlighted the importance that the Mayor placed on tackling this issue . The charge was to be part of a series of measures to improve the transport system in London and was to combined with public transport improvements and increased enforcement of parking and traffic regulations . The report stated that the scheme was expected to be the most effective in reducing through traffic, reducing congestion both within and outside the zone, improving the speed of buses and the quality of life in central London . It was stated that improved traffic flows would make London more attractive to business investment . Substantial net revenues were anticipated, which were to be invested in London's transport system . It also states that 90% of those who responded to a consultation on the scheme, viewed reducing traffic congestion in central London as' important' . </P>

When does the congestion charge have to be paid