The 2004 European Parliament election was the United Kingdom's part of the wider 2004 European Parliament election which was held between 10 and 13 June 2004 in the 25 member states of the European Union. The United Kingdom's part of this election was held on Thursday 10 June 2004. The election also coincided with the 2004 local elections and the London Assembly and mayoral elections. In total, 78 Members of the European Parliament were elected from the United Kingdom using proportional representation. The Conservative Party and the Labour Party both polled poorly. The Conservatives experienced their second-lowest ever recorded vote share in a national election (even less than their 1832 nadir, although the party would do worse still in the 2014 and 2019 elections), and Labour their lowest since 1918. The UK Independence Party (UKIP) saw a large increase in support, increasing its number of MEPs from 3 to 12 and on popular vote pushed the Liberal Democrats, who themselves had increased their representation from 10 to 12 seats into fourth place. In Northern Ireland, Sinn Féin beat the SDLP in the polls and took its first Northern Ireland seat. Background Electoral system The United Kingdom elected 78 Members of the European Parliament using proportional representation. The United Kingdom was divided into twelve multi-member constituencies. The eleven of these regions which form Great Britain used a closed-list party list system method of proportional representation, calculated using the D'Hondt method. Northern Ireland used the Single Transferable Vote (STV). As a consequence of the 2004 enlargement of the European Union, the number of seats allocated to the United Kingdom was fewer than in 1999. It was the first European election to be held in the United Kingdom using postal-only voting in four areas: the North East, North West, Yorkshire and the Humber, and East Midlands regions. Regional seat allocations A combination of the effects of the Treaty of Nice and the 2004 enlargement of the European Union meant that the number of seats allocated to the United Kingdom for the 2004 election was reduced from the 87 MEPs allocated for the 1999 election to 78 MEPs. As a result of the successful challenge of Matthews v United Kingdom before the European Court of Human Rights in 1999 residents of Gibraltar, voted in the European Parliament election for the first time, as part of the South West England region. 1 Includes Gibraltar, the