The Scottish National Party gained its first seat at Westminster in 1945 and became a party of national prominence during the 1970s, achieving 11 MPs in 1974. However, a referendum on devolution in 1979 was unsuccessful as it did not achieve the necessary support of 40 per cent of the electorate (despite a small majority of those who voted supporting the proposal) and the SNP went into electoral decline during the 1980s. The introduction in 1989 by the Thatcher-led Conservative government of the Community Charge (widely known as the Poll Tax), one year before the rest of the United Kingdom, contributed to a growing movement for a return to direct Scottish control over domestic affairs. The electoral success of New Labour in 1997 was led by two Prime Ministers with Scottish connections: Tony Blair (who was brought up in Scotland) from 1997 to 2007 and Gordon Brown from 2007 to 2010, opened the way for constitutional change. On 11 September 1997, the 700th anniversary of Battle of Stirling Bridge, the Blair led Labour government again held a referendum on the issue of devolution. A positive outcome led to the establishment of a devolved Scottish Parliament in 1999. A coalition government, which would last until 2007, was formed between Labour and the Liberal Democrats, with Donald Dewar as First Minister. The new Scottish Parliament Building, adjacent to Holyrood House in Edinburgh, opened in 2004. Although not initially reaching its 1970s peak in Westminster elections, the SNP had more success in the Scottish Parliamentary elections with their system of mixed member proportional representation. It became the official opposition in 1999, a minority government in 2007 and a majority government from 2011. In 2014, the independence referendum saw voters reject independence, choosing instead to remain in the United Kingdom. In the 2015 Westminster election, the SNP won 56 out of 59 Scottish seats, making them the third largest party in Westminster.