their best ever result with 4% of the popular vote. In Scotland, the Scottish National Party gained 50% of the popular vote, winning all but three of the 59 seats, mostly at the expense of the Labour Party. Following the EU referendum held in June 2016, which resulted in a majority of 52:48 to leave, David Cameron resigned as Prime Minister and was replaced by Theresa May. In June 2017, May called a snap election; but the Conservatives lost their overall majority and had to rely on the support of the 10 MPs from the Democratic Unionist Party to continue in Government. The following two years were dominated by attempts to pass through Parliament a negotiated deal on the terms for leaving the EU, but these were opposed by both Brexiteers and Remainers in the Conservative Party, as well as the Opposition parties. Eventually, Mrs May resigned and Boris Johnson became Prime Minister. After further government defeats, a general election was held in December 2019 - the first December election since 1923 - which resulted in an 80-seat majority for the Conservatives, gaining many seats which Labour had held since at least 1945. The United Kingdom formally left the European Union on 31 January 2020. 1979–2010 This period saw five prime ministers, with Margaret Thatcher and Tony Blair the two longest serving post-World War II prime ministers in the UK (the other prime ministers during this period being John Major, Gordon Brown and David Cameron). There was also a mini-revival of the Liberal Party which, after a merger with the Social Democratic Party became the Liberal Democrats and increased their seats in parliament from 11 in the 1979 election to 62 in 2005. Following their victory in 1979, the Conservatives were also successful in the subsequent three general elections, resulting in 18 years of continuous power. The newly formed Social Democratic Party and the Liberal Party contested the 1983 and 1987 elections as the SDP-Liberal Alliance. Although the combined parties achieved a popular vote of 22.6% in 1983, they initially failed to make a breakthrough in terms of seats, winning 22. The Labour party won a landslide victory in 1997 and were also successful in 2001 and 2005. The now merged Liberal Democrats also improved their seat count in this period. The outcome of the 2010 election brought about the first hung parliament since 1974. The victorious Conservative Party accepted