Polling round-up: the 2019 general election, week 4

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The 2019 general election is nearly over. Just 9 days remain until Britain will vote in its 3rd election in just 4 years, continuing a journey that began with the unexpected 2015 election result and was followed by the unexpected 2016 referendum result, which itself was followed by the unexpected 2017 election result. In all three cases, most opinion polls completely failed to predict the actual result: the polls predicted a hung parliament in 2015, a victory for Remain in 2016, and a Tory majority in 2017. None of those things happened.

Week 4 of the 2019 election campaign just ended, and Labour clearly did well last week. After only increasing their vote share by 1pt in Week 2 and Week 3, Labour's average vote share in polls rose by 3pts last week. It is now averaging 33% - exactly the same as in Week 4 of the 2017 election campaign. The Tories, meanwhile, appear to have finally peaked at 43%, and are doing worse than at this point in 2017 (when they were averaging 46%).

So, without further ado, let's look at the numbers.

What the polls looked like in Week 4 (25th November-1st December)

In the week of 25th-1st December, the average of polls was (changes since the previous week): 

Tories 43% (-), Labour 33% (+3), Lib Dems 13% (-2), Brexit 4% (-), SNP 4% (-), Greens 3% (-)

According to my seat estimate, the seat result would be (changes since the previous week):

Tories 348 (-12), Labour 219 (+13), SNP 41 (-), Lib Dems 19 (-1), Others 23 (-) 

The Tories' estimated majority, which last week was 70 seats, has now fallen to 46 seats. Labour have increased their vote share and estimated seat total (the only party to do so).

The Liberal Democrats, meanwhile, have collapsed further, falling to just 13% in the polls and 19 seats in my seat estimate. It is worth bearing in mind that, 7 months ago, the Lib Dems' estimated seat total was 60 seats. It is now just 19 (-41). Amongst Remain voters, the Lib Dems have collapsed still further, whilst Labour is winning the support of almost 50% of Remainers.

Amongst Remain voters, voting intention in Week 4 of the campaign was:

Labour 48% (+4), Lib Dems 23% (-3), Tories 18% (-), SNP 5% (-), Green 3% (-1), Brexit 1% (+1)

Labour's share of the vote amongst Remainers (48%) is the party's highest in a weekly average since the week of 28th February-3rd March, whilst the Lib Dems' share of the vote (23%) is their lowest in a weekly average since 20th-26th May.

Amongst Leave voters, voting intention in Week 4 of the campaign was:

Tories 70% (+1), Labour 16% (+2), Brexit 7% (-1), Lib Dems 3% (-1), Grn 2% (+1, SNP 1% (-1)

How is Labour doing compared to this point in 2017?

MPs voted to hold the 2017 general election on 19th April 2017, so the period of time most comparable to Week 4 of the 2019 campaign was the week of 15th-21st May 2017.

At this point in 2017, Labour was averaging 33%. The Tories’ average poll lead was 13pts, and their estimated majority was 76 seats. By comparison, the Tories’ average poll lead this week was 10pts, and their estimated majority was 46 seats.

Over the following two weeks, Labour support rose steadily until the party was averaging 37%, as shown in the chart below. Labour then outperformed these polls and won 41% within Great Britain in the 2017 election.

Whilst the 2017 campaign was 1 week longer than the 2019 campaign, the final week did not make any difference to the polls; in fact, Labour's average vote share in the final week (36%) was 1pt lower than in Week 6 of the 2017 campaign (37%).

Thus far in 2019, Labour's vote share week-to-week has exactly matched its vote share week-to-week in 2017, as shown in the graph below. If this trend continues, then we should be averaging 35% by the end of this week, and 37% by 12th December. Even if the Tory vote share does not change, this should put us within 6pts of the Conservatives by election day. This would almost certainly result in a hung parliament, with the possibility of Labour becoming the largest party if the polls are slightly wrong (as they were in 2015, 2016 and 2017).