Party Systems in the UK

The way in which parties are grouped and structured in a political system is known as a party system, with a number of parties in contention for political power. There are two ways of thinking about party systems. One is the way they are described in most text books and is based on which parties obtain power, the second is to think about a system as persisting pattern of relationships.

The power approach comprises a number of different models, and it is open to debate which of these best describes the UK system at any given time. It is also important to note that, since the advent of devolution in the late 1990s, different systems have been in play in the component parts of the UK.

Here are the most important models found in a liberal democracy.

·      A one-party-dominant system A number of parties, but only one has a realistic prospect of holding power.

·      A two-party system Two parties compete for power at elections; other parties have no real chance of breaking their monopoly.

·      A two-and-a-half-party system Two large parties are the main players, but are challenged by the growth of a smaller third party.

·      A multi-party system A number of parties contend to form a government; coalitions become the norm.

The relationships approach can be divided in to cooperative and competitive models.

In competitive party systems the relationships are adversarial with single parties winning and holding power, while parties out of power perform the role of an opposition.  In this system the style of politics is antagonistic and conflictual. There is little chance of minor parties achieving or sharing in power and coalitions are rare. The  dominant parties have high levels of party identification from their core supporters but compete for the 'middle ground' by offering a consensus approach to policies.. This system is very descriptive of  UK politics in the period from 1945 to 1974 when the Labour party and Conservative party shared 90% of the popular vote.

In Cooperative party systems, parties in the legislature (Parliament) agree cooperative arrangements for example the Lib/Lab Pact 1978-9 and the DUP/ Conservative Confidence and Supply agreement after 2017. There may also be Coalitions where parties share power for example 2010-15, In this system there may also be election pacts where parties agree not to compete with each other in elections for example the SDP- Liberal Alliance in the 1983 and 1987 Elections.  In this system party support is more volatile with a higher degree of partisan dealignment. Parties will also tend to be more ideologically narrow with their policies directed to securing support form their core supporters. In this sense the system is more adversary than adversarial.

Which of these models most closely fits UK politics at present? 

Traditionally the UK is seen to have a two party system but this is only describes the politics of Westminster. Taken as a whole the UK has a range of party systems and a party system which has evolved. The  era of the two-party dominance was the period 1945-74, when Labour and the Conservatives won, on average, a combined 91 per cent of the votes and almost 98 per cent of the seats at Westminster. This began to change in the mid 1970s and in particular the elections of 1974. Although the Conservatives won large majorities from 1979 to 1997 and Labour from 1997 to 2010 there was a staedy revival in the electoral success of the Liberal Democrats and the emergence of minor parties particularly in the regions of the UK. The share of the popular vote of the  two main parties' combined average  fell to 73 per cent between 1974 and 2017.

However the two-party system persisted, largely as a result of the distorting effect of the first-past-the-post voting system, which limits smaller parties' ability to win seats. The two largest parties continued to share an average of 91 per cent of the seats, and they continued to monopolise government without the participation of the UK's third party. 

The period of coalition government (2010-15) could be described as a two-and-a-half-party system. The Liberal Democrats secured 23 per cent of the vote in 2010 and enough seats to play a part in government, though only as the partner of a larger party in a coalition. Almost 35 per cent of voters supported parties other than the Conservatives and Labour in this election.

However, this proved a short-lived development. The 2015 general election appeared to herald a return to 'business as usual' at Westminster. The Liberal Democrats were devastated at the polls, losing all but eight of their seats. The most startling aspect of the 2015 contest was the landslide victory of the SNP in Scotland, where they took all but three of the 59 seats. However, the SNP is a regional party, which is not a contender for power at Westminster, even if it is able to influence the outcome of some votes in the House of Commons. 

Return to Two Party Dominance?

The 2017 election saw a 'hung Parliament' with no one party having an overall majority. Did this mean a swing away from the two party system? Yes and no. Yes because  the DUP suddenly became very significant by keeping the Conservative government in power but no because the two main parties achieve 82% of the popular vote- which had not happened since the 1960s, the main reason being the Lib Dems failed to recover the losses of 2015 so there were still only two parties with a realistic chance of forming a government. The 2019 election resulted in a more obvious return to two party politics in Parliament  but the two party share of the popular vote fell to 76% - the Conservatives gained clear overall majority and Labour remained the opposition- The Lib Dems again failed to regain their third party position but the SNP increased their representation in Parliament and share of the vote. Essentially  the First past the Post Voting system means Westminster will remain dominated by the two largest parties even though party politics is more fragmented, volatile and more de-aligned than in the period before 1974.

The devolved bodies: a variety of multi-party systems

The use of the Additional Member System (AMS) for elections to the Scottish Parliament and Welsh Assembly has produced very different outcomes from the trends observed at Westminster. A partly proportional system, it tends to increase the representation of smaller parties. Although the SNP has been in power in Scotland for almost a decade now, it formed a minority government from 2007 to 2011 and once again after the May 2016 election. Before 2007 Scotland was governed for eight years by a Labour-Liberal Democrat coalition. Similarly in Wales there have been periods of minority Labour government, a Labour-Liberal Democrat coalition and a Labour-Plaid Cymru coalition.

In Northern Ireland a fully proportional system, Single Transferable Vote (STV), is used to elect the assembly. Until January 2017, when the power-sharing executive collapsed owing to internal disagreement, the first minister and four other members were drawn from the largest party, the

Democratic Unionist Party; the deputy first minister and three others were from the second-largest party, Sinn Fein; and one post was held by an independent. From 2011-16 three smaller parties supplied some members of the executive. It would thus be fair to describe the regions of the UK as having multi-party systems.

On way to understand different party systems is  the using the effective number of parties concept introduced by Laakso and Taagepera (1979) which provides for an adjusted number of political parties in a country's party system. The idea behind this measure is to count parties and, at the same time, to weight the count by their relative strength. The relative strength refers to their vote share effective number of electoral parties (ENEP) or seat share in the parliament effective number of parliamentary parties (ENPP).