The English local election results require careful interpretation. Not all places get them at the same time: a relatively small proportion complete their counts overnight, so the headlines early on Friday morning may not reflect outcomes later in the day.

Overnight the story was one of Labour losses and Reform UK gains, a narrative that has persisted as more results have been declared. By mid-afternoon it was clear Labour was losing more than half of the seats it was defending in England, with some projections suggesting as many as 1,500 losses for the party.

Labour will want to emphasise that these “midterm” elections often go badly for the incumbent Westminster government – but they rarely go quite as badly as this.

The main beneficiary has been Reform UK, which began from a standing start having not contested the previous elections for these councils – and now has more than 600 new councillors, with many more still to declare. These are, though, not the only stories.

Early county council results, for seats last contested in 2021, have shown a more difficult time for the Conservatives in Essex and Suffolk; in Suffolk they lost 40 seats and fell to third place on the council behind both Reform and the Greens.

Results are still being declared, but in London the picture is more nuanced than anticipated. The Green party has made significant – and in the case of their first mayoral win in Hackney, eye-catching – gains, but Labour has perhaps held on a little better here than elsewhere. Nonetheless, the Greens have posed a considerable challenge in other cities, gaining more than half of the seats up for election in Manchester.

The Liberal Democrats have also made gains, and although these are not as dramatic as the rises and falls elsewhere, the party has built on a strong platform from the last time these seats were contested.

Some caution is required in extrapolating from the headlines to voter behaviour. We cannot assume that because Labour has the most losses and Reform the most gains that voters switched directly from Labour to Reform. Even if Labour lose a seat directly to Reform, this may not be because of direct switching between them.

A split vote on the left, for example Labour losing votes to the Green party, can make the winning threshold lower. For example, in St Peter and the Waterfront in Plymouth, Reform gained the seat with 29.4%, from Labour on 28.4% and the Green party in third place on 24.3%.

Meanwhile, a large number of competitive candidates can lead to very low winning shares. In one Birmingham ward, six candidates won more than 10% of the vote each, allowing a Green win with just a 20% share.

It is not possible from the profile of results to infer how voters moved between parties, or how any particular group of voters cast their votes. What we can say is what types of places were more or less likely to vote for each party. Analyses for the BBC and Sky of the results thus far show that decline in the Labour vote share was more strongly correlated with the rising vote share for the Greens than for Reform. The results defy simple explanations, and suggest there are no easy answers for Labour (or the Conservatives) to their polling woes.

This is not just a story of the poor performance of an incumbent government, nor is it only about the sustained success of Reform. Instead, it reflects a more profound change: from the creaking two-party system of a year ago to a fully fledged system of five-party politics in England. This has been evident in polls of Westminster voting intention for some time, with the combined Labour and Conservative share of the vote rarely above 40%, and the Green party challenging for second place with some pollsters. But it is the first time we have seen the full effect of this at the ballot box.

This fragmentation of the electorate across several parties poses challenges for all parties in the first-past-the-post system, though the results in Wales may show that these challenges do not disappear even in a fully proportional system. For both Labour and the Conservatives there are now parties positioned on both their flanks. Turning to either risks losing votes on the other side, and in a system with several parties this can be particularly damaging.

Vital to forging a large enough coalition to form a government is finding messages that unite different fragments of the electorate that may disagree on other things. Failing to do so means the coalition-building must be done between parties rather than within them – a process that will be under way next week at a large number of councils that have moved to no overall control.

The 2024 general election was primarily a story of a highly unpopular incumbent government, but one who lost votes in many different directions. The Labour party is increasingly in the same bind. The Conservative party has so far been unable to shake off that mantle and continues to lose local councillors after two years in opposition. Labour will hope it can find a way to avoid the same fate.