Rishi Sunak has finally agreed a new post-Brexit pact with the EU after months of wrangling.
The Prime Minister and European Commission President Ursula von der Leyen have struck a breakthrough agreement over the Northern Ireland Protocol, a senior Government source said.
The leaders met in Windsor today to rubberstamp the pact, which aims to fix trading issues in Northern Ireland thrown up by Boris Johnson's Brexit deal.
Speaking at a joint press conference the PM hailed the deal - the Windsor Framework - as a "decisive breakthrough" and the beginning of a "new chapter" between the UK and EU.
"It marks a turning point for the people of Northern Ireland," he added.
"Today's agreement delivers smooth-flowing trade within the whole United Kingdom, protects Northern Ireland's place in our union and safeguards sovereignty for the people of Northern Ireland."
A key part of it is an "emergency brake" on changes to EU goods rules that can be pulled by the Northern Ireland Assembly that Mr Sunak said would give the Westminster Government a "veto".
The EU chief also described the deal as "historic", adding: "Today we have reached an agreement in principle of the Windsor Framework. It will allow us to begin a new chapter."
He confirmed at the press conference MPs would be given a vote on the deal - after days of Tory ministers failing to give a clear commitment.
But speaking in the Windsor Guildhall - the location of King Charles and Camilla's wedding - the PM took just two questions from the British media.
He now faces a high-stakes showdown with Tory Brexiteers, who have warned the "devil is in the detail" of the deal.
Mr Sunak has been trying to resolve the mess left by Boris Johnson's deal with Brussels, which the ex-PM later tried to rip up after realising there were problems with the rules governing Northern Ireland.
The Prime Minister has now agreed changes to a key element of the deal - the controversial Northern Ireland Protocol - but getting his MPs to back it will be one of his biggest challenges yet.
He must win the support of the hardline Democratic Unionist Party (DUP), who are furious at the current rules which they say treat Northern Ireland separately to the rest of the UK.
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DUP backing will be critical to getting Tory Eurosceptics on side, as well as breaking the deadlock at Stormont which has left Northern Ireland without a functioning executive.
In an initial statement, the party said it was clear "significant progress" had been made across a number of areas - but said there remains "key issues of concern".
DUP leader Sir Jeffrey Donaldson added: "There can be no disguising the fact that in some sectors of our economy EU law remains applicable in Northern Ireland.
"The DUP will want to study the detail of what has been published today as well as examining the detail of any and all underpinning legal texts. Where necessary we stand ready to engage with the Government in order to seek further clarification, re-working or change as required.
"Ultimately the party will now assess all these proposed outcomes and arrangements against our seven tests, outlined in our 2022 Assembly Election Manifesto, to determine whether what has been published meet our tests and whether it respects and restores Northern Ireland’s place within the United Kingdom.”
Ex-Cabinet minister Jacob Rees-Mogg said on Monday that if the DUP are against the new pact, "there will be quite a significant number of Conservatives who are unhappy".
"I'm afraid with all the EU deals the devil is in the detail, so when people say 'we need to see the legal text', they are not larking about, they really want to see it to understand what the effect is."
Last week, Boris Johnson also refused to say whether he will back the deal negotiated by his successor in No10.
Instead he claimed that the "best way forward" was to press on with legislation he tried to force through Parliament to allow the UK to rip apart the deal he signed without EU consent.
Mr Rees-Mogg claimed the former PM's position will be "fundamental".
But in a major boost for Mr Sunak, Brexit ultra Steve Baker offered his support.
The Northern Ireland Office Minister, who had been on resignation watch, told broadcasters: "I can only say this: that the Prime Minister is on the cusp of securing a really fantastic result for everyone involved."
Keir Starmer said it is "almost inevitable" that new pact agreed by the PM will include some oversight by the European Court of Justice (ECJ) - a major sticking point for hardline Brexiteers and the DUP.
Despite having not seen the details of the deal, the Labour leader again suggested Mr Sunak could count on his party's support.
"Yes, we haven't seen the deal yet, but I'm completely across what the issues are and what the practical solutions are," he said.
"Frankly, any step in those directions is going to be an improvement on what we've got, which is why I can say with confidence we expect to be able to back the deal.
Mr Starmer added: "It's not going to be a surprise, it's not going to be out of the blue, we've been working on these problems for a very, very long time and know what some of the solutions are."
