Who “won” the European Parliament elections?

With almost every result in, we can confirm that these elections have been a big success for the Brexit Party.

Nigel Farage’s new party won 32 per cent of the popular vote, or more than 5.2 million votes. Under the proportional representation system used to allocate seats, that means The Brexit Party gets the most MEPs in Britain: 29.

The Lib Dems saw their share of the vote surge, while both Labour and the Conservatives lost ground.

Does this mean the Brexit Party will clean up at the next general election?

Previous experience suggests that Mr Farage should not be measuring the curtains for Number 10 Downing Street yet.

This is partly because people tend to vote very differently in European Parliament elections than in Westminster elections, and partly because of the quirks of Britain’s First Past the Post electoral system.

Bad predictor of voter behaviour

In recent years, EU elections have proved to be a poor predictor of how people vote in subsequent Westminster elections.

In the 2014 EU elections, Ukip got the biggest share of the popular vote: 27.5 per cent. Labour came second and the Conservatives were beaten into third place.

But in the General Election that followed, David Cameron’s Conservatives got the biggest share of the popular vote and Ukip only got 12.6 per cent – less than half the share they managed in the EU vote the year before.

In fact, only once in the last 20 years has the result of an EU election correctly predicted the winning share of the popular vote in the next General Election: when David Cameron’s Conservatives won in 2009 and again in 2010.

The latest opinion polls that asked people how they would vote in the next General Election have put support for the Brexit Party at between 12 and 20 per cent, much less than the 32 per cent they won in the EU elections.

First Past the Post

The way Westminster elections are decided adds a second difficulty for smaller parties like The Brexit Party.

We don’t use a proportional representation system – where the share of seats in parliament is closely linked to the share of the total votes cast.

If we did, Ukip would have got around 80 MPs in the 2015 General Election. Under First Past the Post, Nigel Farage’s previous party got just one seat in the Commons.

Under First Past the Post, a lot of popular support for a party can be wasted as votes go to losing candidates. In 2015, Ukip came second in 120 constituencies, which meant a huge number of votes did not lead to the return of a candidate.

FactCheck verdict

There are two reasons why the EU results don’t tell us much about what will happen in the next parliamentary elections.

People vote differently in Westminster elections, and the votes they cast don’t win as many seats as you might expect.

The website Electoral Calculus tries to solve both problems by using the share of the vote suggested by opinion polling, not EU elections, and then running it through a model of the First Past the Post system.

The site’s current prediction is that, like Ukip in 2015, The Brexit Party will only win one seat in the next General Election.

Of course, we have to heavily caveat all this by saying that opinion polls have been wrong many times in recent years, and the political landscape is changing so quickly that only a very brave pundit would call the result of the next General Election with too much confidence.

[Update: Electoral Calculus have just published a new analysis where they assume a higher vote share for The Brexit Party and predict that the party could get as many as 15 votes in the next General Election. That would make the party the fifth largest in parliament.]