In the satire 1066 and All That, it is claimed that William Gladstone “spent his declining years trying to guess the answer to the Irish question; unfortunately, whenever he was getting warm, the Irish secretly changed the question”. And now it is the British who have changed the question. Just when relations between Ireland and Britain had reached an unprecedented equilibrium, Brexit makes everything deeply unsettled again.

When James Joyce’s alter ego Stephen Dedalus claims in Ulysses that “History … is a nightmare from which I am trying to awake”, it is surely Irish history he has in mind. But now the Irish have to awake to the living nightmare of British – perhaps we should say English – history.

Brexit is disconcerting on so many levels that it is easy to miss one particularly discombobulating shift. For centuries, there has been a potent contrast between the place of history in the two islands: in Britain, history was over; in Ireland it was continuing on its baleful path.

All the mad conflicts over nationhood and identity and constitutional structures had ceased to trouble the essential British settlement. It was the poor bloody Irish who were still roiled and racked by all that dark passion. There was an Irish question and it was a maddening perplexity. But there certainly was no English question.

And now our little archipelago is turned inside out. We have swapped places. Ireland has, or thought it had, a workable settlement, a way of taming and managing its history. It has been awfully hard-won, carved slowly out of a big block of human agony.

But then up pops the English question. It seems as if these islands must have a fixed quantum of nationalist fervour, a strict allocation of identity crises and cultural neuroses. When it diminishes in the west, it suddenly wells up in the east. The bad habit of defining “us” as “not them” finally wanes in Ireland, but just as it does so it waxes again in England. Britain’s Irish question becomes Ireland’s English question.

For Ireland, our English question is every bit as intimate and excruciating as it is for those in Britain who are still wondering how Brexit came to pass. For good and ill, the two islands are stuck together in a marriage that can be sundered neither by death nor divorce. And in a marriage, you suffer badly when your spouse goes off the rails.

Brexit threatens the Northern Ireland peace process, undermining the Belfast (Good Friday) agreement. It poses the real risk of the imposition of an external European Union border across the fields of Fermanagh and Tyrone. It hurts indigenous Irish businesses whose main trade links are with the UK. To misquote WB Yeats, we are locked in to the Brexiteers’ recklessness and the key is turned on our uncertainty.

The initial reaction to being dragged into the antics of English nationalism has been fury

The initial Irish reaction to being dragged into the mad antics of English nationalism has been one of fury. It is one thing to be made part of someone else’s historic nightmare, but quite another to be given this role by people who seemed not to know or care what Brexit might do to Ireland.

And this applies as much to the remainers as to the Brexiteers. I’ve just read Craig Oliver’s gripping account of the whole referendum debacle from inside Downing Street. I note that the Daily Mail is mentioned 14 times and the Daily Telegraph 22. Game of Thrones, The Godfather and The X-Files all feature. Northern Ireland? Not once. The Republic of Ireland? Zilch. John Bull’s Other Island was apparently cut off by a thick mental fog for the duration of the campaign.

The careless rapture of England’s identity crisis leaves many of us on the other side of the Irish Sea in a cold rage. Tempers have not been calmed by the patronising vagueness of the reassurances that we shouldn’t worry because everything will be all right. It doesn’t help either that at the back of these reassurances is an assumption among some Brexiteers – including some of the Unionist leadership in Northern Ireland – that the Republic of Ireland is not really an independent country, and that it will simply have to follow Britain out of the EU. The suggestion that Ireland will operate UK migration controls at its own ports and airports carries with it the same presumptuous air.

Theresa May and Enda Kenny at a press conference on Brexit in London in July 2016. Photograph: Stefan Rousseau/PA

But anger is of little use. No one knows better than the Irish the chagrin of having your neighbours adopt a superior tone and tell you to get over your funny historic obsessions – so Ireland shouldn’t do that to England now. Instead the Irish government has to do the decent thing for all concerned, which is to try to talk its British friends down from the ledge of a hard Brexit, and to talk its European friends out of pushing Britain off that ledge.

It’s not the kind of job that one sovereign government would normally undertake in relation to another. But in the current circumstances, what has normal got to do with anything?

There are signs now that the vanquished remainers are trying to find a voice. The economic consequences of Brexit are becoming clearer and the ugly tone of the new xenophobia is becoming more repellent to the great British traditions of moderation and tolerance.

There is still time between now and the invocation of article 50 in March 2017 to galvanise a common effort across all the polities of these islands to look for a third way between hard Brexit and no Brexit. While both the Brexiteers and the EU leadership are posing this stark choice between extremes, the mutual interest in achieving a more fluent, ambiguous compromise must not be lost.

Zealots will find this despicable, and claim that compromises never work. But the fact is that the Irish question was solved (in the medium term at least) by just such a creative fudge. The 1998 Good Friday agreement, which came from the intimate cooperation of the Irish and British governments, is a masterpiece of ambiguity. It replaces hard certainties about identity and constitutional status with an open, contingent and deliberately slippery compromise.

It works imperfectly, but it does work – precisely because multiple identities and political contradictions are what we all have to live with – in Ireland, Britain and Europe. It is, in this, a fine model for the kind of creative reconciling of opposing impulses that could solve the English question. And remember that it was much harder to achieve than a sensible semi-Brexit may be because it had to be negotiated across a blood-soaked table.

The Irish government needs to forget protocol and set itself up explicitly as the champion of a soft, ambiguous and contingent Brexit that leaves open the possibility of a return ticket. Keeping Britain within the single market is a vital Irish national interest, and some of us are arrogant enough to suggest that it might be no less vital for Britain.

Before the war of words escalates and positions petrify into irreconcilability, Ireland should make an urgent and coherent effort to plead the virtues of equivocation. If nothing else, Ireland helping England out of a hole would be a historical irony worth savouring.

Visit theguardian.com for Ireland beyond Brexit, a series about the challenges and opportunities the vote has created