Another European Council, another series of tetchy exchanges. So far so familiar, yet an important inflection point was reached at last week’s meeting. For the first time, well, ever, an Irish Taoiseach found himself patronising a British Prime Minister in public.

‘The lack of progress in the negotiations on the withdrawal agreement has been very disappointing,’ remarked Leo Varadkar, in much the same way a class teacher might sum-up the performance of a particularly indolent pupil at the end of term. ‘We still need to see detailed proposals from the UK on how it intends to deliver on the clear commitments it made in December and March.’

Of course it was a statement of the bleeding obvious, but all the more shocking for that. Just months away from the final October deadline the British Government’s final position on Brexit – particularly in relation to the Irish border question – remains as transparent as a pint of stout.

We should not be surprised. Unused to displays of Irish diplomatic self-confidence, there have been three faltering responses from British ministers towards Brexit and the border issue.

Naturally enough, the first has been sheer indifference. ‘Don’t worry Paddy, we’ll get to you.’ This was reflected in Theresa May’s Lancaster House speech about the mechanics of Brexit back in January 2017.

She promised to deliver a ‘practical solution’ on the Irish border ‘as soon as we can’ with all the wafty nonchalance we have subsequently come to expect from British ministers. The level of disregard about the complexities involved has been epic.

Matters are set to conclude, we are told, with a crunch cabinet meeting at the Prime Minister’s country retreat, Chequers, this Friday. Ministers will be expected to stay up late to thrash out a final position on Brexit. (Clearly, the gravity of the situation demands an all-nighter, however the lack of bedrooms for dozing ministers adds an element of British farce to proceedings).

Anyway, the second phase was to treat the Irish Government as perfidious Eire – the ‘Now, look here Paddy…’ approach. This was perfectly summed up by the juvenile briefings to the British tabloid media against Leo Varadkar, culminating in The Sun calling him ‘naive’ and suggesting he should ‘shut his gob’ about the border.

It was also David Davis, the Brexit Secretary, complaining about the Irish Government playing hardball, suggesting this had stymied progress. ‘We had a change of government, south of the border, and with quite a strong influence from Sinn Féin, and that had an impact in terms of the approach,’ he said back in April.

Tone deaf and factually inaccurate, Davis’s curious analysis of Irish politics was upbraided by both Varadkar (‘strange’ and ‘inaccurate’) and by foreign minister Simon Coveney (‘way off the mark’ and ‘nonsense’).

Given Brexit is fundamentally driven by the chauvinists of the Tory right, they are most comfortable when scolding and belittling other nations. It comes naturally, stemming from a sense of self-entitlement from a British governing class that cannot quite comprehend Ireland is not a bit part player it can kick around.

So Varadkar’s other remarks at the European Council at the weekend will have sent the blood pressure of Brexiteer hardliners skyward:

‘[The UK] needs to understand that we’re a union of 27 member states, 500 million people. We have laws and rules and principles and they can’t be changed for any one country, even a great country like Britain,’ Varadkar said.

‘Any relationship that exists in the future between the EU and the UK isn’t going to be one of absolute equals: we’re 27 member states, the UK is one country, we’re 500 million people, the UK is 60 million. That basic fact has to be realised.’

Coming from the least ‘green’ Taoiseach in recent memory, it underscores just how inept British diplomacy towards Ireland has been. Dublin should have been a natural ally throughout this process, keen to secure a deal that minimises disruption to trade and security.

This brings us to the final phase. This can be summed up as ‘Paddy, be reasonable…’ Charm to follow charmlessness? Up to a point. What has really happened is that the balance has tilted. Having self-ejected from the club, John Bull has gradually realised that Paddy has 26 other mates still inside.

It has not been possible to isolate Ireland. The Commission has backed the Irish Government all the way, partly to face down Britain in the negotiations, but also to defend the EU’s integrity, cognisant, no doubt, that other Member States may have similar ideas about departing in future. The Commission was never going to make this easy for Britain. The net result is that Ireland and the EU are indivisible.

Frozen out and with few options, Theresa May needs to decide whether she wants to reach an accommodation, or whether British business will have to brace itself from the calamitous fall off a hard cliff edge in a ‘no deal’ scenario.

Varadkar was at pains to make the point the other day that Ireland wants a deal with Britain. All it requires is for Theresa May to make good on commitments already given. Having conceded in March to abide by a backstop in relation to Northern Ireland – ensuring there will be regulatory alignment and no hard border with southern Ireland – she would be a fool not to follow through.

Having had the idea of a customs partnership and electronic border arrangements (‘max fac’) publicly disowned by everyone who understands these issues, Theresa May will need to summon the courage to confound Brexiteer ultras later this week.

The Guardian reports that her ‘third way’ option might be to commit the UK to remaining in the customs union for goods, avoiding a hard border. It will not be enough, though, to avoid conflict between the determined Remainers and ardent Brexiteers in her cabinet.

Whether it’s sufficient for the EU-27 will depend not only on Michel Barnier’s reaction, representing the European Commission, but also on Leo Varadkar’s, on behalf of little old Ireland.

What a turnaround. A British prime minister’s fate rests on the approval of the Irish. A wry smile is breaking out on the ascetic countenance of Eamon De Valera’s ghost.

Kevin Meagher is the author of ‘A United Ireland: Why unification is inevitable and how it will come about’