While the two-party system is dead, its legacy is thriving by the division of British parties into two party families, a Left family of Labour, the Liberal Democrats and Greens, and a Right family of Reform UK and the Conservatives. With the current Electoral Calculus predicting only a 32 percent chance of one party winning a parliamentary majority, a majority government would require the support of a family of parties.
Simple arithmetic currently stands in the way of a Left family governing. Together, Labour, the Liberal Democrats and the Greens have the combined poll support of 45 percent of voters. However, thanks to the three-way division of support – Labour is 'highest' at 19 percent – the family appears likely to win only 178 seats. There is a one in ten chance that the Left family could get 294 seats. But it would still fall short of a parliamentary majority even in that optimistic scenario.
The two parties in the Right family, Reform UK and the Conservatives together are supported by 48 percent in current polls. Because their support is less divided than in the Left family, this would give the family of the Right 402 seats. Reform's predicted share is seven seats short of a majority. It would take a coalition of up to ten parties, including Muslim MPs and Ulster Unionists, to carry a vote of no confidence against Reform. However, with Reform having the support of just 29 percent of voters there is a 57pc probability that Reform would get less than 300 seats and thus need support from its Conservative sibling.
The Conservatives and Reform UK belong to the same ideological family. The Conservatives can claim to be the senior family member, whereas Reform is the offspring of Nigel Farage's fourth marriage to a political party. Most Reform voters are ex-Conservatives and ex-Conservative ministers defecting to Reform claim to be doing so because it is the true heir of national conservatism. Whereas the Tories have lost one-quarter of their support since the 2024 election and are predicted to win only 83 seats, Reform has doubled its share of voter support.
The distribution of the benefits of a coalition government of the Right would be politically challenging. Nigel Farage has stated that he wants Reform to supplant the the Conservatives as the party of the Right. For Kemi Badenoch being deputy prime minister to Nigel Farage is inadequate reward for presiding over the death of the Conservative Party. However, her ambitious colleagues joining Reform gain a chance to be a Cabinet minister in the next parliament rather than spending another five years in opposition.
In theory a new Centre Family could be created. Surveys indicate that at least a quarter of survey respondents place themselves in the middle of a left-right scale. This would involve the Conservatives giving priority to economic policies rather than competing with Reform on immigration and the Liberal Democrats deciding that there was no point in co-operating with a Labour Party that faced a disastrous loss of seats at the next general election.
Attractive as a Centre Family is to the significant number of voters orphaned by the failures of the Starmer government and the threat of a Reform government, there remains a practical psephological difficulty. On current showing, the Conservatives and Liberal Democrats are predicted to win only 147 seats and many of their easiest gains would involve taking seats from each other.
Prof Richard Rose's, Britain's senior psephologist, is the author of "The Disruption of the British Party System", due for publication in June.