What Would the British Party System Look Like Under Proportional Representation?

Surveying the party systems of other countries can offer lessons for what Britain might expect from adopting a proportional voting system. The experience of New Zealand shows that even when replacing its first-past-the-post system with a German model of PR, it retained aspects of the left-right adversarial politics of its majoritarian heritage. Britain under PR would likely do the same.

Debates over electoral reform are invariably about what party system would emerge. Some believe the Liberal Democrats would be perennial kingmakers. Others suggest that a ‘progressive alliance’ on the centre-left would sweep all before it. On the other side of the spectrum, Nigel Farage advocated for PR predicting ‘a coalition of common sense’ would form between the Conservatives and a UKIP-type party.

But moving to PR will not simply lead to the distribution of representatives more closely matching the existing vote shares. Instead, freed from the problem of ‘wasted’ votes, the electorate is more likely to shop around in a fragmented electoral marketplace. Parties will face a collective choice between a ‘polarised-pluralist’ and a ‘two-bloc’ party system. Moderate pluralism, a staple of the British PR debate, is unlikely to be viable.

Three different systems of multi-party government

The British debate around PR often adopts Maurice Duverger's classic contrast of electoral systems. In this, first-past-the-post (FPTP) produces two-party systems and single-party majority governments whilst PR produces multi-party systems and coalition governments. Although there is some truth to this, it is overly simplistic and conceals the diversity present amongst European multiparty systems.

This article focuses on three generic multiparty systems. The first is ‘moderate pluralism’, where fragmentation is low, distance between parties is small and ‘overlapping’ cabinet alternatives are available. This reflects the West German system from the 1960s to the 1980s, with two major parties alternating with the help of a smaller liberal party. The second is ‘polarised pluralism’, originally applied to postwar Italy, which entails a more fragmented system where centrist governments face ‘bilateral’ oppositions of far-left and far-right. Majority governments are formed by a revolving cast of mainstream parties, with one or more invariably remaining in office after each election. The final type, seen in Scandinavia and southern Europe, involves parties dividing into two ideological blocs, offering voters a choice of governing coalitions. This system encompasses all parties, with radical-left and radical-right parties incorporated into the blocs. Cabinets are single-bloc affairs, formed by whichever wins a majority.

The European experience of PR

Before assessing which system would emerge in Britain under PR, it is worth considering some relevant continental trends. As partisan dealignment loosened bonds between voters and older parties, west European multiparty systems fragmented. Older catch-all parties shrank and new ones emerged, many of them ideologically radical. This has rendered classic moderate pluralism less viable.

One manifestation of fragmentation has been the splintering of previously strong social-democratic parties. On the right, once hegemonic Christian democrats have been supplanted by conservative-liberal parties and have lost support to radical-right parties campaigning on immigration and crime.. As catch-all parties shrank and new entrants emerged on left and right, the mainstream parties had to decide how to respond. In many moderate-pluralist countries, green parties were invited into the governing cartel, whilst the radical-right and radical-left were penned behind a cordon sanitaire. Consequently, many countries with overlapping structures of government formation are now closer to contemporary polarised pluralism.

What would be the shape of a British multiparty system?

European parliamentary elections, held under PR, indicate what might happen if it was adopted in Britain. The performance of UKIP and the Brexit party demonstrate the space available for a radical-right party. On the left, the Greens may be able to emulate continental ecological parties that entered governments. Notably, there was no significant force on the British radical left, with its supporters generally organising within the Labour Party for fear of electoral oblivion under FPTP. Left-wing voices have increasingly made the case for PR, which would make a separate party feasible. The centre-ground would also change. There is a significant ideological gap between the Liberal Democrats and the Conservatives, although some Tory Remainers represent an extant tendency for conservative-liberalism. Under PR, they need not cohabit with socially conservative Eurosceptics.

Assumptions that a moderate-pluralist party system would emerge with the Liberal Democrats as kingmakers fail to reflect this fragmentation and the growth of ideologically radical parties. These have made this system less viable in western Europe and the same would probably be true of Britain. As well as the growth of minor parties, the European experience points to a party system in which Labour and the Conservatives were each down to 20–30 per cent of seats and too small to easily secure a legislative majority.

This leaves either polarised pluralism or a two-bloc system. In the case of the former, extremes on the far-left and far-right would be excluded by their more centrist ideological opponents. It would rely instead on a structure of overlapping coalitions, with the major parties joining together in grand coalitions. In Britain, to maintain this cordon sanitaire, Labour-Conservative coalitions may be required for legislative majorities. Yet the ideological distance between conservatism and Labour’s social democracy is wide. Traditional conservative parties have less to gain from this exclusion of radical parties than others, suggesting that a two-bloc system may be more appealing to the British Conservatives.

A bloc-based party system could leave the Liberal Democrats in a quandary. They survive under FPTP because they fulfil a specific role as an anti-Conservative party in constituencies where Labour cannot win. It is open to question whether space would exist for a left-liberal party, hemmed in by Labour, in a two-bloc system. There would be space on the centre-right—but that might not appeal to most Liberal Democrats. Alternatively, they might stand aloof from the blocs, playing kingmakers for left or right. This is risky in a bloc-based party system, where an uncommitted centrist party would be inviting voters to abstain from government selection.

The prospect of PR

PR in Britain would fragment the party system, with a two-bloc system most likely emerging and boosting non-centrist parties. In this, it would retain the voters’ ability to select governments, the principal virtue claimed for FPTP. When all parties belong to one of two ideological blocs, voters know that in voting for any given party, they are choosing a governing bloc, as well as an option within that bloc.

The prospects of Britain adopting PR look remote at present. The same was once true of Brexit. A hung Parliament, some Liberal-Democrat leverage and shifting opinion in the Labour Party could precipitate movement. If it does happen, European experience points to a release of latent fragmentation, but with elections continuing to offer voters clear governing choices.