These European elections are a chance for the progressive parties to recapture lost ground

For those who believe the British people have a democratic right to pass judgment on the terms of any Brexit deal in a Final Say referendum, it is important the parties sympathetic to that view get solid popular backing

Whatever you do, get out and vote on Thursday (EPA)

For a set of elections that were never supposed to happen, the selection of the new British members of the European Parliament has assumed an unprecedented importance.

Ever since direct elections to the then European Assembly were inaugurated in 1979, these contests have rarely drawn much of a turnout or much excitement, especially in Britain. Now, for the first time – and not a little ironically – the turnout in Britain may be higher than the EU average. Certainly they are the centre of national attention.

True, past European parliamentary elections could occasionally be spectacular expressions of protest and dissent – for the Greens in 1989, Ukip in 2014 – but, on the whole, the results told the nation little it didn’t already know from the opinion polls.

This time will be different. This time the European elections do matter. They are not a second referendum; but they are a chance for the people to try to make their views plain, as best they can, on a transcendent issue.

Europe, whether we like it or not, is the central question; indeed, for all intents and process, the only one. So much is this the case that the Conservatives and the Brexit Party haven’t even bothered to publish a manifesto, an extraordinary state of affairs. So even if the voters wanted to take a view on where they stood on, say, the NHS or animal rights, they cannot. All is Brexit; Brexit is all.

The obvious reasons for this political monoculture are the long agonies of Brexit itself, and public frustration with them; and, as a part of that, the return of Nigel Farage and the rise of his policy-free, strangely structured Brexit Party, currently enjoying an examination by the Electoral Commission.

However, it would be a mistake, though a tempting one, to treat these elections as a proxy second referendum. There is a facile belief sometimes pedalled that totting up the votes of Ukip and the Brexit Party on the one side, and the Liberal Democrats, Change UK, Scottish and Welsh nationalists, Greens, Sinn Fein, the SDLP and various others on the other, will produce some sort of “verdict” on Brexit. It cannot, for the simple reason that the Conservatives can at best be regarded only as a soft Brexit cause; while what Labour actually stands for is as opaque as ever. The numbers, as so often during this Brexit theatre, do not add up.

Some might have hoped that the pro-EU parties could have found a way to work more formally in alliance. That has not happened, in part because Change UK took the view that lack of time made it impossible. It may be that they and the Liberal Democrats, at least, work more closely together in future battles.

Still, for those, such as The Independent, who believe that the British people have a democratic right to pass their judgement on the terms of any Brexit deal in a properly constituted “Final Say” referendum, it is important that the parties broadly sympathetic to that view enjoy solid popular backing. As such, we would encourage you to vote for the progressive party of your choice, be it the Liberal Democrats, Change UK or Greens (or SNP, Plaid and others, depending on where you live).

It will be a further piece of evidence of the growing support for the only logical resolution of this intractable question, one that parliament remains unable to settle.

Indeed, the showing of the pro-referendum parties may well understate the support for such a vote, given that Labour voters (like members and MPs) are overwhelmingly in favour of a further plebiscite, as are, probably, a minority of Conservative and even some Brexit Party supporters (especially if they think that is the only way they can secure their version of Brexit).

Given that the elections are being fought on a proportional system, voters will have more genuine choice than in the Westminster first-past-the-post system, as there is much less probability of a “wasted vote”.

However, the British system is one of the less proportional of proportional systems, and, thus, raises the question of tactical voting. For example, if a pro-Europe voter wishes to make sure that one of their parties wins the last seat in a multi-member constituency – say the tenth out of the 10 that will be returned from South East England – they might vote for Change UK to beat the Ukip candidate for the “last” of the seats, given that Change UK and Ukip are both likely to poll badly.

Indeed, it is worth noting that, whatever your preferred party among the progressives, the political centre ground will feel a more dynamic place if Change UK avoids a humbling outcome this week.

Elections can be surprising affairs, but these ones seem certain to deliver the Tories a historic mauling, falling to their lowest ever share of the vote in a set of national elections (since the Great Reform Act of 1832, that is), no matter how much they dismiss them as irrelevant. In some regions – London and Scotland, for example – they may finish fifth, a humiliating state of affairs.

Even if Theresa May had not already signalled her decision to resign, such an outcome would have helped propel her out of Number 10 in short order. The great likelihood is that Boris Johnson will, after a good deal of fuss, replace her, and attempt (and fail) to secure a “no-deal” Brexit. The time that EU Council president Donald Tusk begged Britain not to waste when the Article 50 process was extended until 31 October will have been squandered in an internal Tory party battle.

What is more unpredictable is how these elections will move the dial within Labour. The local elections proved that the party’s ambiguity over Brexit and a second referendum is not serving it well. These European elections will be an even more emphatic warning.

The great majority of Labour voters, of potential Labour “swing” voters, of Labour members, especially those in Momentum, activists, MPs and MEPs believe that Labour must commit itself to a confirmatory referendum in all and every circumstance, and stop toying with the fantasy of a general election. No Tory is going to vote for a snap election after seeing this premonition of what Nigel Farage could do to them.

The message to Labour’s leadership on Brexit and the referendum is loud and clear. Now will Jeremy Corbyn heed it?