By Stephen Fisher, 6th May 2022.

The BBC Projected National Share (PNS) of the local election vote 2022 is Con 30, Lab 35, LD 19, Others 16.

There is an explainer of the methodology at https://electionsetc.com/2022/05/04/understanding-the-local-elections-projected-national-share-pns-in-2022/.

Historically, party performance in local elections has followed a similar pattern of change over time to the general-election vote-intention opinion polls, as shown the graph below.

Changes in the PNS this year are broadly in line with changes in the polls relative to both 2018 and 2021. The Conservatives are down 7 in the polls since both 2018 and 2021, and down 5 and 6 points respectively in the PNS. Labour are at the same level in the polls and PNS as they were in 2018, but up 4 points in the polls and 6 points in the PNS since 2021. 

In both the polls and the PNS the two parties were tied in 2018. After Boris Johnson became PM the Conservatives achieved a lead that won them the 2019 general election and lasted through to 2021. Following partygate and various other controversies, that lead has been reversed. This week’s local elections essentially confirmed the message from the polls that Labour are now ahead.

In recent years the Liberal Democrats have revived their tendency to do much better in local elections than they do in general election vote intention polls. That pattern was established in the 1980s with the Liberal Alliance, but ended after the Lib Dems joined the coalition in 2010. This year the party continued its post-coalition revival. They are up 2 or 3 points relative to both 2018 and 2021, in both the PNS and the polls.

Its not such a consistent pattern with respect to other baselines.

Indications from the local elections for the next general election?

The Projected House of Commons’ seats from the PNS (with changes from the 2019 general election) is

Con 253 (-112)

Lab 291 (+88)

LD 31 (+20)

Others 75 (+4)

The Projected House of Commons takes into account differences in local and general election voting on recent occasions when the two kinds of election have been on the same day.

It is a kind of a nowcast from the local elections. But we can also ask about whether the PNS tells us something about subsequent general election results that might be years away.

The graph below shows PNS leads (on the x-axis) and subsequent general-election leads for local election years when the Conservatives were in government. The vertical red line represents the PNS lead for Labour this year. The diagonal line is the standard regression line, often referred to as the best-fit straight line. With this data it doesn’t fit very well though. Still it clearly slopes upwards. The bigger Labour’s PNS lead the bigger their eventual general election lead tends to be.

The 2022 lead is not as good for Labour as those in 1990 and 2012. After those years Labour lost in the 1992 and 2015 general elections respectively. The 5-point lead in the PNS this year is not sufficient to claim that Labour has previously won the next general election whenever a PNS lead of that size has been achieved.

But where the two lines in the graph cross suggests the average historical trend and today’s PNS together point to a modest Labour lead in votes at the next election. That would also produce a Labour lead in seats with uniform-change assumptions

The two clusters of years in the graph remind us that there has only been one transition from Conservative to Labour government since the PNS started. The 1997 landslide was heralded by big Labour leads in the PNS, both under Blair in 1995 and 1996, but also under John Smith in 1993 and 1994. All the other local elections under Conservative governments involved more modest Labour PNS leads, or no lead at all. They were all followed by a Labour loss at the general election.

But that doesn’t mean Labour can’t win a general election with a more modest lead in future. They could win power with no lead at all.