The most recent 24 contests illustrate this, with the main parties gaining and sometimes losing seats.
These elections provide something more when a broader perspective is taken. The results show a change in control in almost half. The two main parties each lost four seats, but the Conservatives gained five and Labour just one. The Liberal Democrats took three Conservative seats but lost one in exchange and two others to Independents.
The explanation for some results lies in changing patterns of competition – major parties deciding to withdraw from the fray, Independents leaving or joining the battle for votes, local issue-based parties finding more traction.
But delve deeper still, and something more interesting emerges. Labour is not just losing seats but also vote share. Barely a week into the national campaign, Greg Cook, Labour’s former polling expert, tweeted that the party’s vote had fallen in 85 of 88 recent council by-elections when compared with every year from 2016-2019. Labour’s true position might be worse than the national pollsters are suggesting.
We have results from more than 500 by-elections since the June 2017 General Election. For each ward election there is a before and after – the main May election and a subsequent by-election. Cook’s comments relate to the difference in vote share across these elections.
The local electoral cycle means that comparisons should be made across different years. County vacancies are compared with the May elections held a month before the last General Election. Some district vacancies being contested now were fought last May.
Regardless of the base year, the results are almost entirely bad in Cook’s selection of less than 100.
Taking a broader view, assessing the more than 500 contests since the last General Election, tracks the main parties over time.
Compared with a May 2017 baseline, the Conservatives are down six percentage points, Labour is down one point and the Liberal Democrats are up five. Set the baseline at May 2018 instead, and the Conservative and Labour vote has dropped by two and eight points respectively while the Liberal Democrats have risen by nine points.
Comparing those numbers with our national estimates of party vote shares in both 2017 and 2018 supports Cook’s analysis of the sizeable electoral challenge now facing Labour.
The evidence from council elections runs parallel, with the latest polling showing the party below 30 per cent. As is generally the case, Liberal Democrat support in by-elections is several points higher while Conservative support in by-elections and the polls is similar.