Bernardine Adkins talks to BBC News about claims that the UK would have no tariffs under GATT XXIV

Carrie Gracie: The two candidates for the Conservative Party leadership have been setting out different approaches to how the UK should leave the EU. Boris Johnson says Britain must leave on 31st October, deal or no deal. But the Foreign Secretary Jeremy Hunt says that could trigger a general election if Parliament rejects a no deal Brexit. Our political correspondent Jessica Parker has the latest on the campaign.

Jessica Parker: It's a date, 31st October to be precise. And these two rivals differ on that deadline. He says he's ready…

Boris Johnson: To come out on October the…

Talk Radio Presenter: 31st.

Boris Johnson: 31st, correct.

Talk Radio Presenter: Come what May.

Boris Johnson: Come what May.

Talk Radio Presenter: Do or die?

Boris Johnson: Do or die.

Jessica Parker: He says it's not so simple.

Jeremy Hunt: Well I think that 31st October come hell or high-water deadline is a fake deadline.

Jessica Parker: Campaigning in Chelmsford today Jeremy Hunt squeezed in some shopping for his wife.

Jeremy Hunt: She does like her orchids.

Jessica Parker: And rejected the idea that Boris Johnson's harder line might play better with party members.

Jeremy Hunt: I'm the person who will get us out quickly because I will be able to negotiate with the EU and negotiate a deal through parliament.

Unknown Correspondent: But not do or die which is what Boris is saying.

Jeremy Hunt: Well the trouble with do or die is you could end up with a general election, Corbyn in Downing Street and no Brexit at all.

Jessica Parker: But coming into bat for Boris Johnson this ex-leadership contender says Jeremy Hunt shouldn't flirt with an extension.

Dominic Raab: There's a certain naivety in negotiating terms of saying well actually, yes, we'd be open to an extension. That of course invites the EU to double down.

Jessica Parker: Even if they differ on deadlines there are similarities between the two contenders. Both say they want to get a better deal out of the EU, but that they are also prepared to leave without one if Brussels doesn't budge. And so far, the EU has been pretty clear that the withdrawal agreement is not up for re-negotiation.

Accused of a submarine strategy Boris Johnson surfaced quite a lot yesterday, sticking to the claim that free trade can continue if the EU allows, even in the absence of a full formal agreement. But is such a route really possible?

Liam Fox: It requires both parties' cooperation. So, the ability to use it in a no deal scenario is far less likely to be applicable.

Jessica Parker: No one's accused Jeremy Hunt of hiding away. The self-described underdog knows that ballot papers start dropping through Conservative Party members' doors in ten days' time. Jessica Parker, BBC News.

Carrie Gracie: Well, Bernardine Adkins is with me now, she's head of EU Trade and Policy at law firm Gowling WLG. Thanks so much for coming in. So where do you stand on all of this?

Bernardine Adkins: In terms of this Article 24…

Carrie Gracie: Yeah.

Bernardine Adkins: It isn't workable. I mean the short answer is you need an agreement with the EU. Two people have to wish to take part in this Article 24. The long answer is this is not what Article 24 is about. It comes from the GATT agreement from 1947. It's concerned with goods only. And the idea was to liberalise global trade. The basic premise is no discrimination between contracting parties.

So, the Article 24 was an exception to that to allow some countries to come together to have more free trade between themselves. And it put protections in for the third countries. So essentially it says well it's possible to…if you want to take some time to implement your trade agreement, you can do so and it'll be called an interim agreement. But there has to be oversight of the third countries if you're going to do so, to ensure that they are not discriminated against and treated unfairly.

So, what has happened as a matter of practice since I think 1995, because of the differences in treatment between a full-blown trade agreement which is on implementing now, and one with an implementation period, is people don't use that provision. So, I think we've had 300 free trade agreements, notified to GATTs, but people have not used the interim implementation period, although it does happen in practice.

So quite frankly it's largely something of a redundant provision that people are reading like the law of property act. And I'm afraid it does not give the solace that people are looking for.

Carrie Gracie: And I suppose it's probably worth mentioning that Boris Johnson's conceded that his plan does require approval…

Bernardine Adkins: Yes.

Carrie Gracie: …from the rest of the EU. But he says it's still an option. Do you think it's kind of an option in a game of chicken, assuming the positive energy and that it's going to concentrate minds in Brussels when they see Boris Johnson bearing down on them in a game of chicken?

Bernardine Adkins: Let's assume for argument's purpose they are bowled over by Boris Johnson's charisma and they say yes, we can have an agreement. So, then you have to have a free trade agreement. And people really need to focus on what we mean by a free trade agreement. And if you look at the free trade agreements that the EU have concluded with countries close to…such as Switzerland or the association agreements with Ukraine, they are all about a level playing field.

And so straight away you are into adopting the EU rules on state aid, competition, climate control, environmental, health and safety. All the rules that the Brexiteers wish to escape, because the Brexiteers say we wish to leave the EU to de-regulate. So, we need to focus on what do we mean by a free trade agreement? So straight away, even if the EU says we'll put this withdrawal agreement to one side, let's get an agreement, it is very, very unlikely to satisfy the Brexiteers or even Boris Johnson who already complained that the withdrawal agreement creates us as a vassal state.

Well a free trade agreement will very much do that as well. It means we will very much remain within the regulatory orbit of the EU and that is something people really need to focus on.

Carrie Gracie: So obviously Boris Johnson, front runner, Jeremy Hunt, also in the race, if you were advising what would you tell them is the way out of this?

Bernardine Adkins: To my mind it all hinges on Northern Ireland, the peace process. It all swings around that. What are they going to do to preserve that peace process? And it isn't simply about the…

Carrie Gracie: Give me a solution or assuming that…

Bernardine Adkins: There isn't… Well I have huge difficulty in seeing there is a solution. And already the EU released the mapping to say these economies are so integrated it's a very, very delicate situation. It will so much hinge around that, and the delicacy of that situation. They have to create a solution there and the rest will follow.

Carrie Gracie: But if you've said there isn't one and yet both of these potential leaders are committed to getting out, in Boris Johnson's case obviously by 31st October and in Jeremy Hunt's possibly a few days later, something has to be sorted with the EU on trade and economic relations. So what is it?

Bernardine Adkins: I do think we are playing with a Rubik's Cube and a lot of the pieces are missing. Especially once you factor in the need to preserve that peace process, because you need to preserve it vis-à-vis the US for example. Nancy Pelosi has already said you can go whistle for a trade agreement if you walk away from your commitments under that peace process. And we will essentially be seen as something of a rogue state if we've walked away from that peace process.

Carrie Gracie: Bernardine Adkins, on that rather sombre note, thanks very much for joining us.