Posted by Dr Hannah Bunting
27 January 2026
2025 saw profound changes in the electoral landscape, affecting the competition for seats, the distribution of votes and a decline in vote share required for winners. Not only is it a departure from the previous forty years of contests, but it also has implications for who will win this May, and how they will win.
In England and Wales, there were 313 council by-elections in 2025. The mean average turnout was 30.2% with a low of 12.3% (Whalebone, Barking & Dagenham) and a high of 49.6% (Broadheath, Trafford).
Electors that did turn out to vote were often spoilt for choice. When looking only at those 308 elections where a single vacancy was being filled, the ballot paper listed between 6-8 candidates in more than a third of cases.
Over the previous forty years, an average of only 7% of contests featured as many candidates. The previous high, in 2024, saw only a fifth of by-elections produce this level of competition.
Much of this phenomenal rise is explained by the exponential increase in Reform UK’s local election presence.
In 2022 the party fought only a handful of vacancies. By the following year it was challenging in an eighth of wards and by 2024 it had reached a quarter. It was only in July of that year that the party captured its first by-election seat – a gain from the Conservatives in the East Riding of Yorkshire. By the autumn though, it was making inroads into Labour as the government’s electoral honeymoon turned sour.
But 2025 unveiled a picture of an entirely different magnitude. Reform fielded 290 candidates for 319 vacancies across England and Wales – a rate of 91% and an almost four-fold increase on the previous year.
Reform is not the only party making a serious foray into council elections. The Greens too have been steadily recruiting more candidates.
In 2015 the party contested more than half of by-elections for the first time, a level mostly sustained over the next few years. There was talk of a so-called ‘Progressive Alliance’ with the Liberal Democrats and in some local authorities there was clear evidence that the two parties had agreements about which seats to contest.
But in 2023 the Greens sensed their electoral fortunes were improving. The party increased its candidates, fighting two in every three seats. Over the past two years it has contested three quarters of vacancies. Many electors have the choice of both them and the Liberal Democrats on their ballot paper.
The third strand explaining the rise in candidates is down to the presence of Independents and what might be termed ‘micro-parties’. At one time, Independents were a notable feature of local contests but by the close of the last century only a fifth to a quarter of by-elections saw an Independent on the ballot paper. Over the past three years, however, that fraction has climbed to a third.
Additionally, local-based parties described on the ballot as “… Independents” flourish in some areas, as disillusionment with national politics continues while parties running local councils are regarded as part of the problem rather than its solution. Candidates that are usually collected in the catch-all category of “Others”, contested about one in eight vacancies at the turn of the century but one in four today.
It’s one thing to stand candidates but quite another to attract votes. Here again, 2025 saw new records established. The support required to win a seat has fallen to its lowest level. The number of candidates contesting an election with a realistic chance of success has increased. The gap between the first and second-placed candidates, percentage majority, has narrowed to its lowest margin.
Up until 2025 the mean average vote share for a winning candidate was 52%. The record high share, 55.4%, was established in 1997 when Blair’s New Labour was both a formidable Opposition and then proved a popular Government.
In only seven years since the early 1980s have winners registered an average support of below 50%; three of those seven years have come since 2023. And 2025 established a new record average of 44.2% vote share needed for those winning the seat.
The consequence is that some candidates are successful with very little support. The Conservative in Denbighshire’s Prestatyn ward in July won the seat by seven votes over an Independent, with the remaining five candidates within touching distance. The winner’s share of the overall vote was 21.7%. A total of 20 contests were settled after the winner secured fewer than three in ten votes. This compares to ten of the 650 parliamentary seats in the 2024 general election.
As well as the percentage vote for success shrinking, another record was established for percentage majority as contests became tighter. In 1995, the average by-election majority – the difference between the winner and second place – reached a maximum of 25.7%, with a long-term average before 2025 of 21%. This fell to just 16.9% in the past year.
Record numbers of candidates and greater competition for votes, resulting in closer finishes, means a move away from a two- or even three-party system to a more complex party system.
In the same way that economists construct measures to evaluate the competitiveness of markets, election analysts want to measure real competition between parties. Simply counting the number of parties fighting local elections would inflate the picture.
A measure that has proved popular is the Effective Number of Parties (ENP). Effectiveness can be expressed in terms of seats on a council or a legislature (in which case ENPs where s=seats), but here we’ll use it with reference to vote shares (ENPv).
For this exercise each party’s vote share is expressed as a decimal fraction – 25% appears instead as 0.25. If there are four parties, each receiving 0.25 of the votes, then we would measure this outcome as a four-party system.
With first past the post elections, however, the norm for the ENPv measure is seldom as high. This is because the voting system, ‘winner takes all’, generally leans towards encouraging a two-party rather than multi-party competition. For many years those two parties were Conservative and Labour, but the Liberal Democrats certainly attracted votes if not seats. A classic example of a party winning votes but not converting those into seats was Reform UK at the 2024 general election.
Using ENPv as our measure of party competition reveals yet another by-election record established in 2025. You can see our early analysis of the May 2025 local elections here.
In the final two decades of the last century, ENPv averaged 2.4, unsurprising given that most by-elections featured competition between Conservative, Labour and more often than not a third party (the Liberal/SDP Alliance; later the Liberal Democrats). Over the next decade ENPv rose to an average of 2.6 as the Greens and UKIP fought more vacancies. In 2014 it reached a peak of 3.0 as UKIP gained some traction amongst local voters before falling back to 2.6.
And recently? The measure of effective number of parties for the past three years respectively stands at 2.8, 2.9 and 3.3.
This confirms that more candidates are standing for more parties and more voters are choosing to vote for parties across the range of those standing than ever before.
The next set of normal-round elections are just a few months away. The evidence from these by-elections suggests other parties will continue to secure seats from Labour and the Conservatives. Of all the by-election seats that changed hands in 2025, 88% of them were gains to Reform, Liberal Democrats, Greens, or Others and Independents.
Those gains will be achieved on smaller margins. They will likely be closely fought contests between multiple parties, making every vote count.
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