July's update is based on polling conducted after Boris Johnson was elected Conservative leader and appointed Prime Minister. It shows an immediate swing of more than 5pc from the Brexit party to the Conservatives, with the other parties holding fairly steady. This puts the Conservatives back into the lead as the most popular party with the public, according to the pollsters, with an average lead of about 4pc. This is the first time the Conservatives have been ahead of Labour since Britain failed to leave the EU in March, and the (joint) largest lead they have had since the last general election.
The polls also show the Conservatives now have around twice the support of the Brexit party, which reverses the position from two months ago when they were behind the Brexit party in polling support. On these figures, the Brexit party are unlikely to win many seats directly, but they can still stop the Conservatives from winning marginal seats from other parties.
Some press comment has suggested this 'bounce' is smaller than Theresa May gained in July 2016, when she took over from David Cameron. But using a like-for-like comparison (change in party support using an average of four polls just before and just after the new PM takes over), the 'May bounce' was a bit lower, being less than 4pc compared with more than 5pc for Johnson. Other comment has suggested that the immediate gain in support is transient, and will rapidly fade away. This was not the experience of Theresa May whose lead over Labour was maintained and enhanced for nearly a year, and only evaporated during the general election campaign of 2017.
But while this change is good news for the Conservatives, they would not enjoy the results of a putative general election tomorrow. On these figures they would win about as many seats as Theresa May did in 2017. They would be on the cusp between a minority government and one with a small majority, winning around 310 seats. That would not be enough for the government, even with continuing DUP support, to push through a controversial legislative agenda.
| Party | Polls (%) Old PM | Polls (%) New PM | Change (%) | Predicted Seats | Seat Delta (Seats/%) |
|---|---|---|---|---|---|
| CON | 24.1% | 29.7% | +5.6% | 311 | 15 |
| LAB | 25.5% | 25.4% | 0.0% | 224 | 13 |
| LIB | 17.5% | 18.2% | +0.7% | 43 | 4 |
| Brexit | 20.0% | 14.6% | −5.5% | 0 | 1 |
| Green | 6.4% | 5.1% | −1.2% | 1 | 0 |
| SNP | 3.2% | 3.2% | 0.0% | 50 | |
| PlaidC | 0.6% | 0.6% | 0.0% | 3 | |
| UKIP | 0.6% | 0.8% | +0.2% | 0 | |
| DUP | 10 | ||||
| SF | 7 |
For the Conservatives to get a working majority, they have to increase their support in the polls. A useful rule-of-thumb is given by the 'seat delta' which indicates approximately how many more seats each party would win if its support increased by 1pc. Both the big two parties have a seat delta of around 15 seats for each 1pc. So an increase in Conservative support of 1pc would gain them about 15 seats, which would take them (just) to an overall parliamentary majority. Each additional increase in support of 1pc would add another 15 seats, which would increase their parliamentary majority by 30 seats (since every new seat adds two to the majority).
This means that, for example, a Conservative increase of 3pc more in the polls could give them a comfortable majority of around 60 seats. And in the other direction, a decrease of 3pc would leave them 60 seats short of a majority and out of government.
For the Labour party, the challenge is to unite the left-of-centre voters who are still split across itself, the Liberal Democrats and the Greens. Around 49pc of the public support one of those parties, but Labour has barely more than half of that total. At the moment, the Lib Dems and the Greens are strong enough to wound Labour, by splitting the left-ish vote, but are not strong enough to replace it. Labour needs to win back many of those voters. A recent poll by DeltaPoll suggested Labour could gain 9pc if Jeremy Corbyn was no longer leader of the Labour party, but it didn't ask about particular successors.
In summary, the Conservatives are back, the Brexit party is down, and the two-party system is more relevant again. But a few percentage points of support can change the result considerably, making a wide range of potential outcomes possible. Electoral Calculus will give you the central forecast, as well as the probabilities of various outcomes to quantify the uncertainties. It's going to be an interesting autumn.