At the 2017 general election over 82% of the electorate voted for the Conservative and Labour parties. It was the highest combined vote share for the two major parties since the 1970 general election. The United Kingdom Independence Party vote collapsed, the Scottish National Party fell from the giddy heights it had achieved in 2015, and the Liberal Democrats remained slumped in post-coalition torpor. The Greens barely got a look in. The British electorate’s promiscuous flirtation with insurgent parties was over. Observers proclaimed the return of the two-party system.
Political science textbooks have an explanation for this called ‘Duverger’s Law’. It postulates that under a voting system like First-Past-the-Post, in which the candidate with the most votes is elected as the single representative of a constituency, the electorate will align behind two main party blocs. Third parties will merge or decline, as activists and voters realise that they cannot win. In contrast, proportional representation systems, which ensure that MPs are elected in rough proportion to the vote share of different parties, encourage the development of multi-party politics.
We see clear evidence of this in the UK. Unlike the Westminster Parliament, the Scottish Parliament and Welsh Assembly use proportional voting systems. They contain a large number of representatives of a multitude of parties, from the Scottish National Party and Plaid Cymru, to Liberal Democrats, Greens and the United Kingdom Independence Party, as well as Labour and the Conservatives. The same multi-party politics is true of elections to the European Parliament, the Northern Ireland Assembly, and even the London Assembly, in which Labour and the Conservatives are dominant. Each seems to confirm that with proportionality comes pluralism.
But even if Duverger’s law is right, and First-Past-the-Post pushes voters towards a straight fight between two parties, are we really witnessing a return to the old two party system at Westminster? Before the 2017 election, the combined vote share of the two main parties had been in long-term decline. The peak of the two party system was in the 1950s, when Labour and the Conservatives regularly took over 90% of the vote share between them. By 2015, that had fallen to just over 67%. This reflected the fracturing of the class politics of the industrial society of the 20th century. The dominance of Labour and the Conservatives in the 1950s and 1960s was rooted in the allegiances of voters formed in a society with a mass industrial working class, organised into trade unions, and growing middle and business classes. Each party had millions of members and distinct political cultures, expressed in powerful loyalties and embedded in community organisations and institutions. Voters identified strongly with political parties. By the start of the 21st century, all of this had changed: the class structure and its popular cultures had been transformed, party membership had declined precipitously, and voters had become more fickle in their allegiances.
The post-war two-party system also reflected the heyday of the unified British state, in which people worked for British national industries and institutions, served in the British Empire and its armed forces, and elected representatives to a national Parliament at Westminster. Decolonisation, privatisation and end of the Empire state broke that unitary British state apart. Scottish, Welsh and English national identities and political allegiances have since grown and devolution gives some of them institutional expression.
The most obvious explanation for the apparent return of the two party system is that the 2017 general election was a ‘national interest’ election at which voters expressed their Brexit preferences. The Conservatives increased their vote share amongst Leave voters, and Labour, despite its calculated ambiguity on the Brexit issue, became the repository of Remain or soft-Brexit voters. The continued weakness of the Liberal Democrats and the collapse of the UKIP vote meant that the two-party vote share increased substantially.
These circumstances may never be repeated. If Britain leaves the EU on relatively ‘soft’ terms, voters who turned to UKIP to limit immigration or reject the EU outright may seek representation beyond the Conservative Party once again, just as voters across Europe have turned to nativist and Far Right parties in recent years. There was some evidence for this in polls taken after the Chequers agreement was published. Conversely, if Labour is seen as complicit in Brexit, its vote may splinter and the Liberal Democrats may rebuild their position. Liberal Democrats will have taken heart from some green shoots of recovery at the recent local elections. Nationalist parties in Wales and Scotland will continue to draw strong support, particularly if Brexit threatens the devolution settlement. And the Green Party will continue to attract younger cosmopolitan voters.
None of this renewed pluralism requires the creation of a new centrist party. The messy and volatile politics of a more fractured and complex electorate, divided along lines of age and education, as well as class and nation, may yet return. Don’t bet on a two horse race.