If the UK takes part in the European Parliament elections, then the total number of MEPs will remain at 751 instead of dropping to 705. But when the UK leaves the EU, the number of seats will drop to 705. Because it is likely that the UK will leave the EU early on in the life of the new parliament, we have kept our main focus on what the European Parliament will look like based on 705 seats - that is, without the UK. We still think that these are the most relevant numbers.

But we know that there are readers out there who are curious about what the European Parliament will look like with the UK taking part in elections. So, here's how things will look if we still have MEPs from the UK after the election. The short answer is:

• The main danger to protecting our basic values is still that all the mainstream political groups contain anti-values parties and that these are getting stronger.
• Brexit will have a mixed effect on the European Parliament's ability to protect basic values. Pro-values coalitions and anti-values coalitions are both easier to create if the UK doesn't take part in the elections and will be easier to create once Brexit happens.
• Without the UK, our main tracker shows that it is theoretically possible that an anti-values coalition could scrape together a majority. If the UK takes part in the elections, then an anti-values coalition looks unlikely to reach a majority.
• Without the UK, the majorities of pro-values coalitions are larger. If the UK takes part in the elections, then the majorities of the different pro-values coalitions are narrower. But they do remain feasible.

We're still basing this on the same data from Politico's European Elections poll of polls website.

How are political group sizes affected by Brexit?

The political groups hardest hit by Brexit, relative to their size, are the ECR, EFDD (which won't exist after the elections) the S&D group and the Greens. That's because British MEPs aren't distributed evenly among the political groups.

Having said this, Brexit isn't going to affect the problem we outlined in the main tracker: that anti-values parties inside the mainstream political groups are growing in strength.

{{#open-1}}Tell Me More{{/open-1}}

{{#hidden-1}}Of the 71 currently sitting MEPs from the UK, 19 are in the ECR, 18 are in the EFDD, 18 are in the S&D group, 6 are in the Greens, 3 are in the ENF, 2 are in the EPP, 1 is in ALDE, 1 is in GUE and 3 are 'non-inscrits'. The EFDD is the only anti-values group that is going to take a big hit from Brexit because it contained MEPs from Farage's Brexit Party (formerly UKIP). Though this group won't exist after the elections anyway.

The anti-values parties that we identified in the EPP, S&D, ECR and ALDE groups aren't affected by Brexit because they're not from the UK. So the basic problem we outline in the main tracker, which is that anti-values parties are getting relatively stronger compared to their political group, remains unchanged.{{/hidden-1}}

Here's what the current polling data shows us the new European Parliament will look like if the UK takes part in the elections. Just as is the case without British MEPs, the EPP and S&D group together still can't make a majority by going into coalition together.

There are some notable differences between this and the results if the UK doesn't take part.

Who's bigger if the UK takes part? The Greens would have a handful more seats, and so would the ALDE group.

Whose predicted result isn't really affected if the UK takes part? Well, nobody actually!

Two other groups are going to take a hit in the elections, but if the UK takes part in the elections, the size of this hit will be smaller. So, the S&D group still shrinks, but not by as much if the UK takes part in the elections. The same with the ECR.

And two groups will actually do better in the elections if the UK does not take part. That's the EPP and the EAPN. Want to know why?

{{#open-2}}Tell Me More{{/open-2}}

{{#hidden-2}}The EPP is predicted to get 178 seats if the UK does not take part in the elections. And only 171 if the UK does take part in the elections. And the same thing happens with the EAPN. It would have 3 more seats if the UK does not take part in the elections. That sounds counter-intuitive. The reason for this is probably that when the UK leaves the EU, some of its 73 seats will be redistributed to other countries. And several of those seats would happen to be in countries where the EPP and EAPN are doing well with voters. So, imagine that you're in a country that has 20 MEPs, and the EPP is predicted to win 50% of the seats. The EPP would get 10 seats. Imagine that country was reallocated two extra seats after some UK seats were redistributed around the EU. Then you're looking at a total of 22 seats. And 50% of 22 seats is 11. If you don't understand why some UK seats will be redistributed after Brexit, take a look at our methodology.{{/hidden-2}}

The 'non-inscrit/new/5 Star Movement' category of MEPs would get larger.

{{#open-3}}Tell Me More{{/open-3}}

{{#hidden-3}}The main reason the 'non-inscrit/new/5 Star Movement' category gets larger is because Farage's new Brexit Party hasn't yet committed itself to join any political group. In the current European Parliament it's part of the EFDD group, where it is the biggest member, but that group will stop existing. Italy's 5 Star Movement, the second biggest group in the EFDD, is trying to form a new political group.{{/hidden-3}}

Pro-values coalitions

In a European Parliament of 751 seats, you'd need 376 to scrape a majority. Our main tracker looks at 3 pro-values coalitions that could be made if the mainstream political groups decided to kick out their anti-values parties. How does the situation change if the UK takes part in the elections?

The EPP, S&D group and ALDE could form a Grand-Liberal Coalition with around 379 MEPs, giving them a majority of 3. This is smaller than the majority that this coalition would produce if the UK wasn't taking part in the elections (which would be 15).

The EPP, S&D, the Greens and GUE could form a Super Grand Coalition of around 390, giving them a majority of 14. Again, this is smaller than the majority that this coalition would produce if the UK wasn't taking part in the elections (which would be 24).

The EPP, S&D, ALDE and the Greens could form a Grand/Green Plus Coalition with around 434 MEPs, giving them a majority of 58. Once more, this is smaller than the majority that this coalition would produce if the UK wasn't taking part in the elections (which would be 65).

So, the UK taking part in the elections makes the majorities in the pro-values coalitions narrower than if the UK doesn't take part. Put otherwise, once Brexit happens, pro-values coalitions would actually produce bigger majorities. There are three reasons why the majorities that can be achieved with these pro-values coalitions are smaller if the UK takes part in the elections.

{{#open-4}}Tell Me More{{/open-4}}

{{#hidden-4}}

The first reason is that the total number of MEPs is higher: 751, compared to 705 after Brexit. Of course, a majority of 751 is bigger than a majority of 705. The second reason is that all the possible pro-values coalitions involve the EPP and S&D, and two of them involve ALDE. Of these, only the S&D really gets a boost from the UK staying in the EU, and even then it's not enough to compensate for the fact that the number needed to reach a majority is bigger. The third reason is that the EPP is actually going to be larger once the UK leaves the EU. That's because some of the seats belonging to UK MEPs are going to be redistributed among other EU countries, and the EPP seems to be doing well in some countries that are being allocated more seats.

{{/hidden-4}}

Anti-values coalitions

So, what happens to the two anti-values coalitions we examined in the main tracker? Remember that this is a hypothetical proposition - Manfred Weber, who is the EPP's candidate for Commission President,recently said that his political group would not cooperate with other anti-values political groups. For anti-values coalitions, we actually see a similar effect to what happens with the pro-values coalitions. That is, it looks like they become harder to create. The story is a bit more complicated, but on balance it looks like it would be harder for an anti-values coalition to reach a majority while the UK is part of the EU.

{{#open-5}}Tell Me More{{/open-5}}

{{#hidden-5}}

The anti-values coalitions look like they're harder to form for two reasons. Again, the total number of MEPs is higher: 751, compared to 705 after Brexit. So the number needed for a majority is higher. Then take into account that the EPP and EAPN don't contain many British MEPs, so they don't get much benefit from the UK taking part in the elections. In fact, both of these groups are going to get fewer MEPs if the UK takes part in the elections because of the way that British seats will be reallocated after Brexit. On the right of the political spectrum, the ECR is the only political group that gets a boost from the UK taking part - they'd get a handful of seats from UK parties.

But the picture is more complicated than this for two reasons. First, there are a couple of considerations that could make the numbers lower in practice. The Polish MEPs in the EPP and the ECR come from rival national parties. The Polish MEPs in the EPP would be likely to walk out of the EPP if the EPP were to cooperate with the ECR. Furthermore, anti-values MEPs from the S&D group, who are nominally left-wing, might not be keen in reality to work with parties on the political right. Conversely, there are a couple of considerations that could strengthen these majorities in practice. The Brexit Party is part of the EFDD, and is set to do well, but this doesn't show through in the coalition numbers because the EFDD is being dissolved. So the Brexit Party is currently not part of a political group - they're floating in the 'non-inscrits/new/5 Star Movement' category. The same goes for the 5 Star Movement, which is trying to form a new group to take the place of its old group, the EFDD. And there are also a number of new and non-inscrits parties that are likely to be considered anti-values in practice but don't (yet) belong to a political group. So there are a significant number of MEPs who don't show up in the anti-values coalition because they're not part of a political group yet. Having said that, it looks like it will be harder for an anti-values coalition to reach a majority if the UK takes part in the elections.

{{/hidden-5}}

A Conservative-Extreme Right Coalition would reach around 302 MEPs, which is around 74 seats short of a majority (versus 46 short of a majority if the UK doesn't take part in the elections or once the UK leaves the EU).

A Conservative-Anti-Values coalition would reach 328 MEPs, which is around - 48 seats short of a majority (versus 22 short if the UK doesn't take part in the elections, or once the UK leaves the EU).

Verdict

As with our main tracker, the main story is this. The theoretical possibility that anti-values parties could scrape together a majority by forming a coalition with the EPP is less likely while the UK remains a member of the EU. Having said this, the EPP has said that it won't work with anti-values parties anyway.

So, the main danger to protecting our basic values is still that all the mainstream groups contain anti-values parties and that these are getting stronger. That's because in the EPP and S&D the group is shrinking while the number of anti-values MEPs is remaining stable or rising. And in the ALDE group, although the group is growing, so is the number of anti-values MEPs. Because anti-values parties can influence what the rest of their group does, they could team up on specific votes with the EAPN and whatever group comes out of the 5 Star Movement's new initiative.

But the political mainstream doesn't need to hold itself hostage to its minority of anti-values members. Mainstream parties can still reach a majority after kicking out their bad applies if they work in coalition with each other - which they're going to have to do anyway because they're not able to reach a majority by themselves.

Find out more:

What exactly does the European Parliament do, and why is it so important? Read this.

What do we mean by 'anti-values', and where do we get our data from? Here's our methodology.

This could be the most important EP elections ever. Why? Watch this.

Take our quiz to see why you should vote in the EP elections.