By Stephen Fisher, 2^nd May 2023.

Changes in vote intention opinion polls typically provide an indication of headline net seat changes at local elections. This year presents a significant challenge to that idea. 

Most of the seats up this year were last fought in 2019. The following table shows how party support in the opinion polls has changed since then.

Table 1. Opinion poll changes from 2019 locals to 2023 locals

With little net change for the Conservatives, Liberal Democrats or Greens, there has been a big swing from the parties which Nigel Farage once led (UKIP, Brexit and Reform) to Labour. We know from surveys that is not the product of much direct switching from Farage parties to Labour. Most of the support for UKIP and the Brexit Party from the spring of 2019 went to the Conservatives by the general election that year. Labour’s more recent rise of support has come disproportionately from 2019 Conservative-Remain voters, even though in absolute terms there have been more Conservative-Leave voters switching to Labour. Also, some of the Labour rise is apparently due to the decline in the numbers of people telling pollsters they know whom they would vote for.

Before thinking about how those general election vote changes might affect local elections this time, we need to reflect on a puzzle from last time. Back in 2019, the Farage parties did not stand many candidates. Many of their supporters must have turned up to the polls but had to look elsewhere for someone to vote for. That was perhaps part of the reason why independents and candidates for micro parties did so well that year. If so, then maybe the independents will do much less well this time now the Farage parties are less popular. But those independents and others who were elected in 2019 might since have built up personal support and benefit as first-term incumbents.

If the rise of Labour in the polls is, to an unusual extent, due to the rise of “Don’t Knows”, it might not translate to gains at the local elections. At around a third of the electorate, local election voters are more engaged and partisan. The rise of the “Don’t Knows” may have been more limited among those who normally vote in local elections. If so, the swing to Labour in the local elections might be smaller than what the polls suggest. 

In addition to those unusual factors, there are the usual reasons why poll swings do not necessarily translate into local election outcomes, especially local politics and selective candidature. 

Nonetheless, I have applied my usual local election seats forecasting models regardless. If nothing else it is interesting to consider the extent to which local election results do track opinion polls, and analysis of the discrepancies is instructive.

by Stephen Fisher, 6th May 2021.

Local election seat gains and losses are hideous to try to predict at the best of times. Various factors make this year especially hard. The Covid-19 pandemic means that the 2020 round of local elections was postponed to today, and there have been various boundary changes and restructuring that mean it is hard to allocate many seats to either the 2016-2020 or the 2017-2021 4-year cycle that my model requires. Nonetheless, and despite the weaknesses of my 2019 forecast (discussed below), I have ploughed on regardless. This is not due to the kind of stoic determination that the Finns call sisu: amusingly summarised by someone as, “chin down and press on to the next disappointment.” Rather, I am still curious as to how much of a guide (on a broad macro level) Westminster vote intention polls are to local election outcomes. 

Headline forecasts are in the table below together with the range of possible outcomes in the model. The table includes the projections from Michael Thrasher’s second scenario here. He and Colin Rallings would normally calculate an expected National Equivalent Vote (NEV) from the results of local by-elections, but those have not been happening. Instead Michael Thrasher has used adjusted opinion polls to estimate the NEV and then projected the implied changes at the ward/division level. Both mine and his methods use polls this year, but whereas Michael’s is a local projection based on previous ward and division level results, mine is based on regression models of the macro historical relationship between poll changes and net seat changes. (For a really micro, individual-level approach, predicting Labour losses in “red-wall” councils, but not overall net gains and losses, see the analysis from YouGov’s Patrick English here.)

Table 1. Forecasts for English local election net seat changes 2021

It is striking that my forecasts point in different directions from Michael Thrasher’s projections for every party. But with 4630 odd seats up for election, both sets of predictions are for modest net changes. The prediction intervals for my forecasts comfortably include zero for all three parties, so each of them could easily end either up or down when all the results are in.