THE Irish Deputy Prime Minister has warned the next prime minister he will not be able to scrap Theresa May’s Brexit agreement and replace it with a new deal.

Simon Coveney said a “change in personality” did not alter the “complexities” and “vulnerabilities” of issues such as ensuring an open border between the Republic of Ireland and Northern Ireland.

His intervention comes after both Boris Johnson and Jeremy Hunt said the backstop solution had to be taken out of any agreement if it were to win the backing of the Commons.

Speaking on the BBC’s Andrew Marr Show, the Tanaiste said: “I think it’s important to say very clearly, if respectfully, that the facts don’t change around Brexit. The complexity doesn’t change, the vulnerabilities around the island of Ireland don’t change and just because there’s a change in personality as British Prime Minister, doesn’t mean that the negotiation of the last three years and the solutions that were designed by the British Government as much as the EU aren’t still as relevant and important today as they were six weeks ago.”

He warned against either candidate pursuing a no-deal Brexit on 31 October, adding: “I think if the approach of the new British prime minister is that they’re going to tear up the Withdrawal Agreement then I think we are in trouble.

“I think we’re in trouble quite frankly because that’s a little bit like saying ‘either give me what I want or I’m going to burn the house down for everybody’. The EU, I think, has made it very clear that we want to engage with a new British prime minister, we want to avoid a no-deal Brexit, but the solutions that have been put in place to do that haven’t changed and just because a new British Prime Minister says they have to change doesn’t mean that the EU collectively will respond to that by changing the approach of the next three years.”

Coveney added there would be a “fundamental unfairness” in offering a fresh agreement to May’s successor, when one had already been negotiated. He repeated that the backstop – which has proved a major sticking point in May’s three failed attempts to get her deal through the Commons – had to remain in any deal, although it could be replaced with alternative arrangements when they arose.

“This is about reassuring people in Northern Ireland that they are not going to go back to the friction and tensions of the past,” he added.

“That is ultimately what this is about and so to ask Ireland to compromise on that core issue when we spent two and a half years working with the British Government and the EU to try and find a way to compromise on all sides to ensure that we don’t face that prospect is not a reasonable ask, because of a political challenge in Westminster to move away from that position.”

He dismissed a provision under World Trade Organisation (WTO) rules, known as GATT 24, which proponents, including Johnson, say would allow free imports and exports to continue while a long-term trade agreement is thrashed out.

Writing in The Sunday Times, Coveney warned a no-deal Brexit would “devastate” Northern Ireland’s economy. “If Britain decides to leave without a deal it would cause huge damage to us all,” he wrote, adding Northern Ireland would be the hardest hit.

“A no-deal Brexit will devastate the Northern Irish economy with tariffs and rules that will fundamentally disrupt the all-island economy upon which so much progress has been built.”