Boris Johnson has put delivering Brexit at the forefront of his campaign to become Conservative leader – and Britain’s next Prime Minister.
He hasn’t always been crystal-clear about some of the detail.
But after interviews with both BBC News and LBC Radio in the last 24 hours, some of Mr Johnson’s vision of how Britain exits the EU is becoming clearer.
Here’s what we have learned from his latest public statements – and the things we still don’t understand.
He accepts that a “GATT 24” agreement won’t work if there’s no deal
Politicians who have called for a hard Brexit – leaving the EU without a withdrawal agreement – have sometimes cited Article 24 of the General Agreement on Trade and Tariffs (GATT).
This piece of legislation allows countries to carry on trading under existing tariff arrangements if they are in the process of negotiating a future free trade agreement.
Mr Johnson mentioned this in the BBC leadership debate last week, when asked what he would do to stop farmers in Northern Ireland paying higher agricultural tariffs if their livestock crossed the border into the Republic.
He said: “There will be no tariffs, there will be no quotas because what we want to do is to get a standstill in our current arrangements under GATT 24, or whatever it happens to be, until such a time as we have negotiated the [free trade agreement].”
Mark Carney, the Governor of the Bank of England, numerous independent trade experts, and even fellow Brexiteer Liam Fox said such an agreement under the terms of the GATT could not work in a no-deal scenario.
By definition, there would be no framework for a future trade deal with the EU, and if no trade negotiations are in progress, Article 24 of the agreement does not apply.
Mr Johnson accepted that in his LBC interview today, saying: “What you can’t do is unilaterally use a Gatt 24 solution, but what you could do is agree with our EU friends and partners is to go forwards together on that basis.”
Basically, it’s increasingly clear that Boris Johnson thinks he can leave the EU with some kind of renegotiated withdrawal agreement in place, in place of the one Theresa May failed to get through parliament.
The EU have consistently said there will be no renegotiation of the deal it struck with Mrs May, but Mr Johnson thinks they could yet make some concessions.
Will we withhold the “divorce” payment?
Mr Johnson has previously suggested that withholding the £39bn “divorce settlement” agreed with Brussels might be one way of putting pressure on the bloc’s negotiators.
We’ve written about the rationale behind this financial settlement at length before. Fundamentally, the UK previously signed up to contribute to EU annual budgets until at least 2020, and there are other financial commitments that might stretch decades into the future.
All this was agreed in some detail and the UK government estimates that the final bill will cost Britain between £35bn and £39bn.
Eurosceptics have tended to seize on this report by the House of Lords EU committee, which found that Britain could leave without paying “as a matter of EU law”.
But Theresa May made it clear in parliament that her government took a different view, saying: “There are legal obligations that this country would hold to the European Union in relation to financial payments.”
And the same Lords report also warned that “the political and economic consequences of the UK leaving the EU without responding to claims under the EU budget are likely to be profound”.
“If the UK wants a preferential trading relationship with EU, including a transitional arrangement, the EU partners may well demand a financial contribution post-Brexit,” the report added.
In recent days the French president, Emmanuel Macron, said that Britain could face a credit rating downgrade if it refused to pay up.
And Günther Oettinger, the European Commissioner in charge of the EU budget, said that international agreements giving UK universities and research projects access to EU programs could be taken off the table if a financial settlement is not agreed.
Do Mr Johnson’s latest comments on this issue represent a softening of tone? When he first floated the idea of holding back the £39bn payment, he said: “I think our friends and partners need to understand that the money is going to be retained until such time as we have greater clarity about the way forward. I always thought it was extraordinary that we should agree to write that entire cheque before having a final deal.
Today he said: “I think the money is more difficult. I think that £39bn is at the upper end of the EU’s expectations, but there it is. It’s a considerable sum. I think there should be a little bit of creative ambiguity about when and how that gets paid over.”
Irish border question still unclear
Boris Johnson says the Northern Irish border is one of the issues that “need to be tackled on the other side of 31 October during what’s called the implementation period”.
If we leave the EU with a deal, the implementation period will begin straightaway and allow both the UK and Brussels to prepare for the next phase: working out our long-term trading relationship. But if there’s no deal in place on Brexit day, there’ll be no implementation period.
Mr Johnson now accepts this (he’s been reluctant to concede the point until now) and says leaving with a deal, and therefore an implementation period, is “what I’m aiming for”.
But that’s not consistent with his claim that we can wait until the implementation period to work out what happens at the Irish border.
It’s hard to work out exactly what he means here, but it sounds like he plans to revisit the existing Withdrawal Agreement to remove or alter the “backstop” – the controversial last-resort position which would avoid a hard border on the island of Ireland, but which Brexiteers fear would trap Britain in the Customs Union.
If that is what he has in mind, he’s got a major problem. The European Commission spokesperson told FactCheck today that “as we have said many times before, it is possible to rework the Political Declaration on the framework of the future EU-UK relationship, but the Withdrawal Agreement [the deal struck by Theresa May] is not open for renegotiation”.
The arrangements for the Irish border are contained in the Withdrawal Agreement. So it sounds like as as far as the EU is concerned, the arrangements for the Irish border have already been decided and cannot be changed.
And if Mr Johnson is not happy with those arrangements, his only option is to walk away from the deal altogether – in which case, there’ll be no deal, and therefore no implementation period, after Brexit day.
He is clearly hoping that Brussels will prove to be more flexible than the position they have set out in numerous public statements like this.
Georgina Lee and Patrick Worrall