Since 1922 the British electorate has returned either a Conservative or Labour Government, leading many to conclude that British politics will continue to be dominated by a two-party system. However, rising levels of public disenchantment with the major parties has seen the popularity of smaller parties, including nationalists, grow. The electoral success of the Scottish Nationalist Party in Scotland and the Liberal Democrats/Brexit Party in the last European Elections have led some to doubt whether the future of the UK's two-party system.
British politics has a long tradition of protest parties who voters have supported as a way of sending a message to the two major political parties without fear of putting them into power. In 2005 the Liberal Democrats received a surge in votes for their anti-Iraq War stance and in 2010 received a sizeable portion of votes rewarding their opposition to university tuition fee rises. In 2015, the United Kingdom Independence Party and the Scottish Nationalist Party made record gains at the expense of the main parties. Even in 2019, the general election debate was shaped in part by the smaller parties and the Scottish Nationalists maintained their status as the largest party in Scotland. Despite the continued popularity of protest parties in British general elections, the UK's first past-the-post-electoral system deliberately favours the two main parties over inflating the amount of seats they receive relative to the percentage they achieve nationwide. Smaller protest parties, while benefitting from disillusionment with the major parties and popular backlash against single issues, often find their voters geographically dispersed. This makes it difficult to translate a high nationwide vote into parliamentary seats. Nowhere was this more evident than in the 2015 General Election when the United Kingdom Independence Party received over 3.8 million votes (amounting to 12.6 percentage of the vote nationally) but returned only one Member of Parliament. This compared to the Conservatives who won just 36.8% of the vote nationally in 2015 but returned over half of all the Members of Parliament.
The Liberal Democrats and the Scottish Nationalist Party can hardly be considered protest parties, as both have been in either the national or devolved government in recent memory. The Liberal Democrats were in Coalition Government with the Conservatives from 2010-2015 and the Scottish Nationalist Party has been in government in Scotland since 2007. Both have also demonstrated throughout their respective periods in government that they are not simply single-issue parties. Similarly, the first-past-the-post electoral system has in the past disadvantaged the Liberal Democrats, notably in the 2010 General Election when they received 22% of the national vote but only returned 9.5% of the total number of Members of Parliament. However, the concentration of votes in Scotland has seen the Scottish Nationalists benefit from the current electoral system. In 2015 the Scottish Nationalists received 50% of all voters in Scotland and returned all but three of the parliamentary seats in Scotland. It is therefore not clear cut that smaller parties will always be disadvantaged under the current system, those that have a geographic concentration may do particularly well under it.
[P1] The UK's first-past-the-post electoral system favours larger established parties. [P2] There will always be a rotating cast of protest parties responding to public opinion on prominent political issues of the day.
Rejecting the premises
[Rejecting P1] The first-past-the-post electoral system favours some geographically concentrated smaller parties. [Rejecting P2] The smaller parties are far from protest parties, Liberal Democrats and the Scottish Nationalists have both been in either the UK or devolved government.