Much media attention has focused on the July 4 UK election won by Labour with a landslide that ranks alongside the party’s other major victories in 1997 and 1945. However, there may be a bigger, long-term reason historians come to regard 2024 as a pivotal political moment — that is, the increasing fragmentation of the UK political landscape. Alongside Labour’s huge win, seats were also gained by the Liberal Democrats, Reform, the Welsh nationalist Plaid Cymru party and the Greens. Meanwhile, the Scottish National Party continues to compete for prominence with the formerly ruling Conservatives. To gauge why this could be so significant, it is necessary to look at the last time the UK experienced back-to-back landslides, in opposite directions, as seen in 2019, with a big Conservative win, and the 2024 Labour victory. Remarkably, this was more than a century ago, in 1900, with a huge Conservative victory, and in 1906, with an overwhelming Liberal win. The 1900 and 1906 elections are historically huge, as they helped catalyze an era-defining realignment that led to the modern UK electoral system. Indeed, the 1906 win was the last time that the Liberals won an absolute majority in the House of Commons, while it was also the last general election in which neither Labour nor the Conservatives won the popular vote. Almost 120 years on from 1906, the UK political system is again showing significant signs of disequilibrium. Most notably, the collective share of the vote won on July 4 by Labour and the Conservatives was the lowest since the end of the First World War. In the volatile, turbulent UK political landscape of 2024, there is a growing possibility that the long-standing Labour-Conservative two-party system could be on its last legs. However, rather than giving way to a new two-party system, as happened in the early 20th century with the demise of the Liberals, it might instead result in the entrenchment of a multiparty system akin to multiple continental European countries. The decline of the traditional two-party dominance is not new. From 1945 to 1970, Labour and the Conservatives collectively averaged more than 90 percent of the vote, and also seats won, in the eight UK general elections held in this period. Yet, the average share of the vote won by the two parties fell significantly in the subsequent nine UK general elections. This brought about significant political change that is, by and large, still unfolding in 2024. The decline of the Labour-Conservative two-party system may make the outlook for UK politics more unpredictable. Andrew Hammond It is the Liberal Democrats, which gained more than 60 seats on July 4, that have probably done more to date to break the hold of the two major parties. From 1974 to 2005, the party’s average share of the vote in general elections, including the Liberal/Social Democratic alliance from 1983 to 1987, was just below 20 percent, although the party slumped in the polls after forming a coalition government with the Conservatives from 2010 to 2015. While the Liberals have long taken votes from both major parties, the overall political impact has probably been greatest on Labour. The success of the Liberal/SDP alliance was one factor that helped contribute to Labour’s long period in opposition from 1979 to 1997, when it endured four consecutive general election defeats before Tony Blair’s premiership. Several other parties have come to prominence, too, including the SNP, which currently governs in the Edinburgh-based devolved parliament, Reform, the Greens and Plaid Cymru. Reform’s predecessor, the UK Independence Party, or UKIP, won the European Parliament vote in the UK in 2014, thus becoming the first party other than the Conservatives or Labour to win a UK national election in more than 100 years. Driven in part by UKIP’s appeal, David Cameron, the prime minister at the time, promised in 2014 that, if he won a majority in the 2015 general election, he would hold an “in or out” referendum on the UK staying part of the EU. So, UKIP had a profound influence on Britain, with the 2016 referendum resulting in a victory for the Leave campaign. The decline of the Labour-Conservative two-party system may make the outlook for UK politics more unpredictable, since it is harder for any single party to secure a majority government. This is despite the first-past-the-post voting system that tends to result in the leading party gaining a significantly larger number of seats in the House of Commons than would be the case under a more proportionate electoral system — a situation that also benefited Labour on July 4. To be sure, coalitions and the sharing of power have long been a feature of UK local governments and devolved parliaments and assemblies outside of Westminster. However, this same dynamic may now become more common at the heart of the UK government itself in London. Until 2010, when a coalition government was formed between the Liberal Democrats and the Conservatives, Labour and the Conservatives had overall majority governments following every election since 1945, except for about six months between the February and October 1974 elections. In 2017, the Conservatives again failed to win an overall majority, forcing Theresa May, the prime minister at the time, to reach a so-called confidence and supply agreement with the Democratic Unionist Party from Northern Ireland. So, the UK’s long-standing two-party system may be giving way to a significantly more unpredictable political landscape. Despite Labour’s landslide, fragmentation is growing, with the Liberal Democrats, Reform, the SNP, Plaid Cymru and the Greens increasingly competing for prominence. Andrew Hammond is an Associate at LSE IDEAS at the London School of Economics.