Irish and British officials had been careful to manage expectations ahead of this first bilateral meeting between the Taoiseach and the new British Prime Minister.

Their message was clear: there would be no breakthrough in Dublin when Boris Johnson met Leo Varadkar.

So there was little surprise when the joint statement, issued after the meeting, was low on specifics: the talks had been "positive and constructive"... they had identified "common ground" but "significant gaps" remained.

Yet swirling around in the background was a dramatic rumour of a possible pathway to a deal: Boris Johnson plumping for a Northern Ireland-only backstop.

Sounds familiar? It should be. 

This had been the original plan to get over the problem of how to ensure there was no return to a hard border in Ireland, despite the UK signing future trade deals with other countries.

The idea would be for Northern Ireland to remain closely aligned with some single market and custom union regulations and there-by obviate the need for any checks and controls with the Republic.

This plan had been torpedoed by the Democratic Unionist Party because it meant that Northern Ireland would be treated differently from Great Britain and this, they feared, risked its constitutional position within the UK.

The DUP's power flowed from their confidence-and-supply deal with the Conservatives. Their crucial votes propped-up Theresa May's government.

So why is the Northern Ireland-only backstop back on the agenda?

The first reason is that the hardline Brexiteers hated the other proposed solution - a UK-wide backstop. A Northern Ireland-only backstop would generate less heat.

Secondly, Mr Johnson has hounded-out Conservative MPs who were opposed to his Brexit strategy and he no longer has a majority at Westminster.

As the DUP no longer hold the balance of power, their capacity to dictate policy has evaporated.

Both the Taoiseach and the British Prime Minister have agreed that optimal time for a deal to be struck, if it is to be struck, would be in mid-October at the next EU leaders' summit.

Mr Johnson said in Dublin that he does want a deal, however he declined to give any details about what it might contain.

He did reference his proposal for an all-Ireland animal health and food safety regime - but this would solve only part of the Brexit problem.

If the British Prime Minister was to accept the Northern Ireland-only backstop, he would be seeking something in return. After all, he has regularly described it as the 'anti-democratic backstop.'

Mr Johnson could demand that the Northern Ireland Assembly would have a role in how and when the backstop is to be applied.  

Yet the Irish government are certain to have reservations about any suggestion that the backstop could be watered down.

If an overall deal could be struck, it would banish the spectre of a crash-out Brexit - including the dire predictions of tens of thousands of job losses in the Republic.

However, striking a deal with the EU is only part the problem facing Mr Johnson. Given he now heads a minority government, the Prime Minister would also have to secure cross-party support at Westminster in order to force it through.

This is treacherous territory.

While Boris Johnson didn't speak publicly about a Northern Ireland-only backstop at today's news conference in Dublin - Nigel Farage is already sensing that the British Prime Minister could be moderating his hardline position.

Farage tweeted: "The Boris bravado has disappeared in Dublin, saying No Deal would be a 'failure of statecraft'. He is now going all out for Mrs May's deal, with Northern Ireland to be hived off from the rest of the UK." 

Allies of Boris Johnson suggest he is not interested in a Northern Ireland-only backstop. If that is accurate, then we are most likely on the road to a 'no deal' Brexit. 

But as Taoiseach Leo Varadkar said today in Dublin, both the EU and UK will end-up back at the negotiating table within a short period of time after any UK crash-out. And when they do - the Irish border will be top of the agenda.