The prime minister speaks for the whole of the UK in foreign policy, but in domestic policy he or she speaks for a parliament divided between government and opposition. The Electoral Calculus analysis of March polls gives a 46 percent probability that after the next election the prime minister will speak for a government that depends on a parliamentary majority divided between two or even more parties.
After a month in which Boris Johnson has been the voice of Britain in foreign affairs stretching from Kyiv to Washington, the probability of the Conservatives governing with an absolute majority is only 15 percent. Even though the voice of the Labour Party has been less heard because it agrees with the Conservative priority of defending Ukraine, the probability of the next election producing an absolute Labour majority is much higher, 38 percent.
The wartime government that Johnson's idol, Winston Churchill led was a coalition government of Conservative, Labour and Liberal MPs. On current polls, there is a 19 percent possibility of the Conservatives winning a plurality but not a majority of seats. In such a situation, a Conservative coalition government would only be possible if Johnson was treated like Neville Chamberlain, ditched in favour of a party leader trusted by other parties.
There is a 38 percent likelihood of Labour governing without a parliamentary majority by gaining the support of a third party that has too few MPs to have a chance of forming a government. This is politically feasible because all Opposition parties want to see the the end of a Conservative government that has been in office since 2010. Moreover, by taking a firm stand against very left-wing policies promoted by Jeremy Corbyn his predecessor, Keir Starmer has made Labour an acceptable coalition partner.
The Labour leadership would prefer to govern with the support of the Liberal Democrats because there is considerable harmony in their policies and the two parties rarely compete against each other for seats in the House of Commons. On the basis of the ward-by-ward and constituency by constituency application of March poll results by Electoral Calculus there is only an 9pc percent probability of this happening. The most likely Liberal Democrat outcome is that it will only win 7 seats in the next House of Commons. This would only add up to a parliamentary majority if Labour won 16 seats more than its predicted total.
Currently, the March polls show that there is a 27pc probabilty of the formation of a Labour plurality government depending on the Scottish National Party. Because its electoral support differs from that of parties fighting English seats, the most likely outcome is that the SNP will win more than fifty seats, about double the number the Liberal Democrats could hope for at their best.
Labour would be confident of governing for two years with SNP support on one condition: it grants the demand of the Scottish Parliament for a referendum on Scottish independence. Even though this is not Labour's current policy, it could easily justify such a deal as a price worth paying for giving Britain a new government. Moreover, if an independence referendum resulted in a defeat for the SNP cause, which Scottish polls show is a real possibility, then Labour would also appear as the defender of the Union.
Richard Rose is Britain's senior psephologist and an expert on party government. His new book 'How Sick is British Democracy?: a Clinical Analysis' is published by Palgrave.