The thorny issue of the Irish border question was perhaps the most pressing concern, at least in terms of the domestic political pressure on Prime Minister Theresa May.
For the European Union representatives, arguably more urgent was the matter of the so-called ‘Brexit bill’ and the rights of EU citizens currently living in Britain.
A deal seemed close on Monday, but was jettisoned by Mrs May’s informal coalition partners in the DUP, who quickly put the kibosh on a deal on the Irish border that was seen by the arch-unionist party as weakening the fabric of the United Kingdom.
Theresa May’s cabinet, and the DUP, seem for now to be united behind the deal that was agreed today, although some ‘hard’ Brexiteers on the Conservative backbenchers are said to be anxious about the size of the bill.
We look at what the deal means for some of the big Brexit issues.
The Irish border
No matter what damage, if any has been done to the DUP/Conservative alliance, it seems that the Republic of Ireland consider themselves rewarded for their hardball stance on the border.
While there is a clause in the agreement (apparently at the DUP’s insistence) that say there will be no regulatory divergence between Northern Ireland and the rest of the UK, avoiding a hard border is clearly the main priority for all sides.
A key section of the agreement says that avoiding a hard border is the ‘overarching requirement’ of any deal, and significantly, says that the UK as a whole will remain in the Internal Market and Customs Union if no deal is reached.
Another significant point is the text’s strict adherence to the Good Friday Agreement, which formalised the rights of Northern Irish residents to be entitled to Irish citizenship, or dual citizenship of both the UK and the Irish Republic.
In effect, the issue of the Irish border remains unsettled, despite both sides’ hailing today’s agreement as a moment of significant progress.
The wording that offended the DUP to the point of Arlene Foster’s jettisoning the deal, has been removed, offering them a victory.
However, it is clear that the demands of Irish premier Leo Varadkar are paramount, and the Taoiseach can be very happy with the negotiation.
Those on both sides of the border, or in the UK, however, who think that the matter is settled could be in for a rude awakening before negotiations conclude.
If the EU were happy about the Irish issue, which amounts to kicking the can down the road, but on a road inherently favourable to them, they will also be pleased with the financial terms of the deal.
While Mrs May has avoided the symbolic £40bn figure that was anathema to many Brexiteers, the estimated £35-£39bn bill is hardly buttons.
Paying that amount of money willingly (though over a period of several years) represents a sharp reversal for some of the more strident Brexit-backers in Mrs May’s cabinet.
Brexit Secretary David Davis dismissed reports of a high bill as ‘nonsense’ and Foreign Secretary Boris Johnson told the House of Commons last month that EU leaders could ‘go whistle’ if they sought a high Brexit bill.
Both men have now signed up for the deal thrashed out overnight, a significant change from their previous hardline stance.
Bumps in the road
Securing a deal doesn’t necessarily mean that Mrs May is in the clear politically, after a difficult few months on the Brexit issue.
As Nicola Sturgeon pointed out, the devil is in the detail of the document that was agreed to today, and already there is unrest among some outside forces who could influence the Government.
Nigel Farage is furious, his default position, and claims that the Prime Minister has betrayed the millions who voted Leave.
His ally in the rebel Brexit campaign, Arron Banks of ‘Leave.EU’, has called for an immediate leadership contest in the Conservative party.
One of the front-runners in any leadership battle, Jacob Rees-Mogg, has been conspicuous by his silence since the deal has been announced.
For now, it appears the Tories are united, but if someone of Mr Rees-Mogg’s stature breaks ranks to criticise the deal, it could open the floodgates.
While there are happy politicians in London, Belfast, Brussels, and Dublin, today’s deal is arguably just the start of the process – and there is much hard and complicated work to be done.