Sky News: Tory leadership race: The view from Brussels

I began by asking them, broadly, what do they make of the campaign to become British Prime Minister so far?

Philippe Lamberts: "I see many people in denial of reality."

Agata Gostynaka-Jakubowska: "I think many of the contenders are actually delusional about what they can achieve. And I think the reality will come to bite them soon."

Jean-Claude Piris: "Sometimes you are obliged, in order to be elected, to make promises you know you are not going to implement so some of them are pushing a little bit too much. Because as you say in English they are promising unicorns - things which are completely unrealistic."

Several of the candidates - Dominic Raab, Jeremy Hunt, Boris Johnson, Michael Gove, Sajid Javid, Matt Hancock among them - have said they will come back to Brussels and successfully renegotiate the deal.

Jean-Claude Piris: "[The candidates] think they have to do that to give some hope to their electorate which is very particular at this time but no, it will not be possible on the side of the EU to do that."

Philippe Lamberts: "Well good luck with that! Doesn't he [Dominic Raab] think that Theresa May already did that. Well actually he did himself [as Brexit Secretary]."

Jean-Claude Piris: "If you are talking about the legal Withdrawal Agreement - the 585 pages - this will not change. What could be changed is the Political Declaration and it's important because it's the future relations with the EU."

What about an eleventh hour backdown by the EU?

Philippe Lamberts: "What many people like Dominic Raab and others are ignoring is the calculus that the EU27 are making is that indeed a no-deal Brexit will be harmful but ruining the integrity of the Single Market would be even more harmful. So if you have to chose between two evils, you choose the lesser one."

Agata Gostynaka-Jakubowska: "Any contender who thinks that he or she will be able to bypass the EU institutions in those negotiations and negotiate bilaterally with key member states, I think he or she is wrong to think this."

A WTO no-deal Brexit?

What about a so-called World Trade Organisation (WTO) Brexit in which the UK leaves with no deal and then trades on WTO terms with the EU and the rest of the world?

Jean-Claude Piris: "That means on 1 November, suddenly the UK will have no trade agreements with anybody in the world so it will be a unique country. And nowadays the UK benefits from the EU Single Market but also all the trade agreements concluded by the EU on behalf of the 28 members with a lot of countries in the world - Canada, Singapore, South Korea, Mexico, Japan and so on.

"All that would be lost on the first day. WTO doesn't bring you anything. WTO obliges you to have same customs tariffs with all countries in the world and all are free to do what they wish with you with their tariffs. It's crazy. It's crazy. Nobody in the world is on a no deal."

The Divorce Bill

Boris Johnson has said that he won't pay the £39bn 'Brexit bill' to the EU unless Brussels comes up with a better deal.

Jean-Claude Piris: "Of course it's possible not to pay. You know that it will put the UK in a very bad way; the way where countries are not respecting their debts - like the Argentinian way.

"The problem is that you will need your neighbours to whom you are owing this money, if you want them to help you to have a trade agreement to arrange the big huge problems of no deal on 1 November."

Philippe Lamberts: "If you want 'global Britain' maybe it's not the best starting point to start reneging on your own legal commitments... And by the way, leaving without a deal proves rather your inability to strike a hard bargain.

"It means basically turning your back on a major trading partner and again that's not a good signal for other trading partners."

The Irish Border issue

The Irish border is the most intractable Brexit issue. Home Secretary Sajid Javid has proposed paying millions of pounds to Ireland in order to solve the border issue.

Jean-Claude Piris: "If it was possible to solve it with money! But it is not. It is a question of war and peace. It's a question of deaths. You know during what you call The Troubles how many deaths there were so we are not sure how things will go."

Others leadership contenders, like Dominic Raab, are suggesting the Irish Backstop should simply be ditched and 'alternative arrangements' put in place.

Agata Gostynaka-Jakubowska: "I don't think that's achievable. I don't think that the backstop can be ditched. That has been said by the EU leaders on numerous occasions."

Philippe Lamberts: "Alternative arrangements have been discussed around the table. This is magical thinking, you know.

"You are in a difficult situation and you hope that Harry Potter or Dumbledore will create a solution out of nowhere to resolve your own contradictions. That won't happen, we live in the real world."

Are there any candidates they think are credible?

Jean-Claude Piris: "There is one candidate I have seen that I think is talking the truth. Rory Stewart, I think is his name, but I have to conclude looking at the news that he has not many chances to be elected."

And finally, any advice for the Tory grass roots who will pick the next British Prime Minister?

Agata Gostynaka-Jakubowska: It is important that the grass roots members who will be voting for the next Tory leader actually reach to perhaps experts - although I know that's not a very popular word these days - and really analyse the trade offs in between leaving the EU without a deal or with a deal because that's a debate which I don't think some of the contenders have been engaging with so far.