Question: What political party stopped the construction of the Thames Gateway Bridge

<P0-S0> The Thames Gateway Bridge was a proposed crossing over the River Thames in east London, England. <P0-S1>  It was first mooted in the 1970s but never came to fruition. <P0-S2>  In November 2008, Boris Johnson, the then Mayor of London, formally cancelled the entire £500 million scheme. <SEP> <P1-S0> Dagenham ( ) is a large suburb of east London, England. <P1-S1>  In the London Borough of Barking and Dagenham, it is 11.5 miles (18.5 km) east of Charing Cross and 9.5 miles (15.2 km) east of the City of London. <P1-S2>  Historically in Essex, it was an agrarian village and remained mostly undeveloped until 1921, when the London County Council began construction of the large Becontree estate. <P1-S3>  The population of the area significantly increased in the 20th century, with the parish of Dagenham becoming an urban district in 1926 and a municipal borough in 1938. <P1-S4>  It has formed part of Greater London since 1965 and is a predominantly residential area, with some areas of declining industrial activity, including the Ford Dagenham plant. <P1-S5>  The southern part of Dagenham, adjacent to the River Thames, forms part of the London Riverside section of the Thames Gateway redevelopment area. <SEP> <P2-S0>  A member of the Conservative Party, Johnson identifies as a one-nation conservative and has been associated with both economically and socially liberal policies. <P2-S1> Alexander Boris de Pfeffel Johnson (born 19 June 1964), known as Boris Johnson, is a British politician, popular historian and journalist. <P2-S2>  He has served as Secretary of State for Foreign and Commonwealth Affairs since 2016 and as Member of Parliament (MP) for Uxbridge and South Ruislip since 2015. <P2-S3>  He had previously been MP for Henley from 2001 to 2008 and Mayor of London from 2008 to 2016. <SEP> <P3-S0> The Mark Morris Memorial Bridge (locally called the North Bridge) is a 2 lane truss bridge across the Mississippi River in the United States. <P3-S1>  It connects the cities of Clinton, Iowa and Fulton, Illinois. <P3-S2>  The bridge may also be known as the Lyons-Fulton Bridge, which was the name of a predecessor bridge and the name listed on the USGS topographical map. <P3-S3>  The town of Lyons, Iowa, was annexed to Clinton in 1895, but the north end of the city is still referred to as Lyons. <P3-S4>  The bridge is the terminus of both Iowa Highway 136 and Illinois Route 136. <P3-S5>  The 1975 bridge was named in memory Mark Morris, a long time member of the City of Clinton Bridge Commission who died in 1972. <P3-S6>  Morris was instrumental in the construction of the 1975 bridge and the City of Clinton Bridge Commission named it in his honor. <P3-S7>  The bridge was opened in January 1975, replacing an older span upstream that once carried the Lincoln Highway, U.S. Route 30.) <P3-S8>  In 1982, Iowa DOT announced that it would be removing a 20 cent toll from the Gateway Bridge and the Mark Morris bridge beginning January 1983. <P3-S9>  Iowa and Illinois agreed to split responsibility for the maintenance of the two bridges with Iowa maintaining the Mark Morris bridge and Illinois the Gateway bridge.