Nigel Farage’s Brexit Party is on course to come first in the European elections, at least if the polls are to be believed.

We should wary of reading too much into any of these polls as predicting the turnout – that is, who’ll actually end up voting on the day – always one of the toughest challenges pollsters have, is going to be an even more difficult task this time around.

There are also a number of known unknowns about the European elections. We don’t know what the consequence will be of holding local elections in half of England a fortnight beforehand. What does that mean for the strength of the volunteer effort from the Conservatives, Labour and the Liberal Democrats? If the Conservatives are given a kicking on 2 May, will their voters and activists want to bother on 23 May? Or will voters who have sent their message “return home” to the Tory party in the European elections? What happens if, as is perfectly possible, the Liberal Democrats emerge as the big winners of the locals? And what happens if a bunch of unlikely voters turn up to either try and bury the hope of another In-Out referendum or to put rocket-boosters underneath it?

These are just some of the unknowable questions. Across England, voters have a choice of three explicitly pro-Brexit parties and three explicitly anti-Brexit parties, while pro-European voters in Scotland and Wales have four anti-Brexit options to choose from. That means that the question of “Who finishes first?” is not very important as far as gauging public opinion goes. Nor will it have that big of an impact as far as the composition of the United Kingdom’s parliamentary delegation goes.

Here are some more useful things to look out for:

Where does the Brexit Party do well?

The biggest barrier to a second referendum is that a majority of MPs don’t want one. There are a lot of reasons for that, but the only one that these elections could change is that a group of MPs – essentially, Labour MPs in small towns and Conservative MPs in Leave-voting marginals – fear what will happen to them if they put the Brexit question back to the people.

It doesn’t really matter if the Brexit Party finishes first, second or third – what matters is whether at the end of the night it has done well enough for MPs to be nervous about what it means in their constituencies. It’s much more important for Farage’s party that it appears to be one capable of winning a plurality of votes in some parts of the country than that it reliably plods along getting a quarter of the vote around the whole of the country.

Can the anti-Brexit parties poll more than 50 per cent of the vote?

Because the barriers to getting another referendum in the first place are quite high, it’s easy to neglect the conversation about what the outcome of another referendum would actually be.

There is a lot of chatter about the failure of the various anti-Brexit parties to coalesce under one party’s banner. This ignores that voters aren’t unthinking blocs to be rearranged at will by politicians, and there are costs as well as benefits to fighting the election as one party. Yes, it would increase the chances of getting pro-Remain MEPs elected but it would also slightly suppress the number of pro-Remain votes.

Why? Well, because not everyone who wants to remain in the EU is comfortable voting for the Liberal Democrats, or Change UK, or the Greens, or the SNP, or Plaid Cymru. There are enough pro-Remain options that, if British pro-Europeans are in a position to fight and win another referendum any time soon, they ought to be able to, in a second-order election, when turnout is relatively low, be able to comfortably take a majority of votes between them.

That’s particularly important because no one disputes that there has been relatively little shift in public opinion since the referendum and the great hope for anyone wanting a different outcome is that anti-Brexit groups – the young, people of all backgrounds who live in big cities, graduates, social liberals – will turn out in greater numbers than they did in 2016.

What does the splintering of the two parties’ 2017 coalitions mean in practice?

For various reasons, the two main political parties have found it convenient to talk up their improved vote share at the last election. Of course, under the rules of our First Past the Post electoral system, vote share doesn’t mean anything: what matters is your ability to turn votes into seats in the Houses of Parliament.

The pattern in both polls and more importantly actual elections since the last election in 2017 is that both the Conservatives and Labour’s overall share of the vote is down, with their voters flitting off to various smaller parties.

Now it may be that an election result in which the Conservatives get 32 per cent of the vote and Labour gets 30 per cent plays out in an identical fashion to the last one, in which the Conservatives got 42 per cent and Labour got 40 per cent. But it could turn out to be quite different.

Just because the two parties are losing voters at the same rate doesn’t mean that doing so will have the same effect. We saw that at the last election: Labour gained a lot more of the 2015 votes share than the Conservatives did, yet only gained 30 seats because a lot of its extra votes were “wasted” – that is, they piled up more votes in seats they already held.

The Conservatives’ vote share, while not as efficiently distributed as in 2015, and nowhere near as well distributed as Labour’s in 2005, was still a lot better distributed than Labour’s.

We also know that there are a lot more places where, as far as the question of who ends up in Downing Street goes, Labour can afford to lose votes and even seats. If Labour loses seats in Scotland to the SNP, that has big implications for Jeremy Corbyn’s freedom of manoeuvre as far as actually passing legislation is concerned. But it has zero implications as far as the question of whether there is a Labour or a Conservative prime minister in Downing Street.

Don’t forget that losing votes doesn’t necessarily equal losing seats. Let’s say that, at the next election, the Conservatives lose votes to the Brexit Party, Ukip and the Liberal Democrats, while Labour loses votes to the Brexit Party, Ukip, the Liberal Democrats, Plaid Cymru and the SNP.

If the Conservative losses to pro-Brexit parties are concentrated in ultra-safe Tory seats, where they have a lot of votes going spare, that is obviously a much smaller problem than if Labour is losing votes to pro-Brexit parties in marginal seats where they need every vote going to win.

Equally, if Labour’s Liberal Democrats problem is concentrated in inner-city seats – where they have plenty of votes going spare, but the Conservatives’ Liberal Democrat problem happens in suburbs where they don’t have votes going spare – that’s obviously less worrying than the reverse.

These elections may help us work out what the revival that the smaller parties are enjoying in the polls might mean at a general election.