While the number of parties winning seats has multiplied, the primary division of parties has shrunk. Instead of being divided between parties of the left, right and centre, seven parties can now be grouped into two blocs. The right-wing bloc consists of two parties, the Conservatives and Reform UK. The left bloc consists of five parties, Labour, Liberal Democrat, Green, Scottish Nationalist and Plaid Cymru.
The traditional swing of the pendulum with votes shifting between Labour and the Conservatives has been overtaken by competition for votes and seats within each bloc. More of Labour's lost supporters are drifting further to left to the Greens under Zack Polanski than turning Tory. More Conservatives disillusioned with the performance of the recent Tory government are moving to Reform UK rather than Labour. This makes sense in terms of ideological affinity as well as formal spatial distance theories.
Analysing the electorate in terms of voting blocs offers hope to the left. Opinion polls currently show the left bloc has 50pc of voters. This is more than double the support of Labour, the leading party of the left, which stands at 19pc. It is also slightly more support than the right bloc has, at 45pc. Within the right, Reform UK has a clear lead over the Conservatives.
Bloc analysis provides a different answer to the question: Which party will come first at the next general election? Among individual parties, Reform UK comes first with 27 percent in the polls, and Labour trails 8pc behind in second place. But when blocs are compared, Labour would stake a claim to take Downing Street because it is the largest party in the left bloc, leaving Nigel Farage as leader of Her Majesty's Official Opposition.
However, Britain is not the Netherlands, where Members of Parliament are elected by proportional representation in a single national constituency. A candidate becomes an MP by coming first in one of the country's 650 constituencies. Thus, we need to turn to MRP analysis to understand the distribution of seats if a general election were held today.
The Electoral Calculus analysis shows that no party is likely to win a parliamentary majority. Reform UK would come first with a lead of 162 seats over Labour, but fall far short of a majority. However, adding 116 Conservative MPs would give the Right bloc a parliamentary majority and make Nigel Farage prime minister supported by whichever Tory was ready to be Farage's deputy.
Although the left may claim more votes, the division of the vote among five parties greatly reduces the number of seats individual left parties can win by coming first in constituencies. Electoral Calculus estimates that the left bloc's chance of an overall majority is only one in four.
Apolitical arithmetic could be used to argue for left parties making a pact so there is only one left-wing candidate in each constituency. The bloc would only need to hold 326 of the 500 seats the parties collectively won at the 2024 election in order to win a majority.
Political arithmetic would say that such a pact is crazy in any language. It would mean that Ed Davey would have to tell more than 500 Lib Dem constituency parties not to contest their seats and to urge their supporters to vote for a Labour government that even the Labour mayor of Greater Manchester currently deems unworthy of support.
The Greens could demand that Labour MPs stand down in dozens of constituencies which the Greens currently appear likely to win from Labour as they did in the Gorton and Denton by-election. While such a Labour concession might prevent seats from going to Reform UK, it would not add to the strength of the left bloc, for Green gains overwhelmingly come from Labour losses.
An electoral pact among parties on the left would not necessarily stimulate a parallel pact on the right. If Reform UK were to stand down in the 40 seats that it is currently predicted to take from the Conservatives, it would still leave the Conservatives with one of their worst election results in history and not increase total number of right-wing MPs.
Nigel Farage has an alternative to a formal pact with the Conservatives. He can ask Tory supporters to vote tactically for Reform UK as the only party of the Right that can save the country from another Labour government. The Electoral Calculus prediction supports such a claim. If an election were held today, the Conservatives would take 29 seats from Labour while Reform UK would take 195 Labour seats.
Prof Richard Rose's book, "The Disruption of the British Party System: A Guide to the Next General Election" is published on 9 June. A paperback edition can be ordered from Manchester University Press at a 30pc discount by citing code 'EVENT30'.