An open letter to Taoiseach Leo Varadkar, signed by 200 Northern nationalists of varying prominence, has called on the Irish Government to address their “frustration” and “sense of abandonment” over Brexit, Stormont, the DUP-Tory Westminster deal and unionist disrespect in general.

“We appeal urgently to you Taoiseach,” it concludes, “and to the Irish Government, to reassure us of your commitment to stand for equality and a human-rights based society and your determination to secure and protect the rights of all citizens in the North of Ireland. ”

Varadkar’s office responded promptly by saying the way to address these issues is to restore devolution.

Given Northern nationalism’s growing ambivalence and even hostility towards Stormont, that may not have been quite the response desired.

The letter in Monday’s Irish News began an immediate game of “spot the Shinner” in Northern Ireland, where tribal antennae are always twitching.

It is true that the 200 signatories included Sinn Féin members, activists, election candidates and quango nominees, with no representation of any other party. Sinn Féin alone welcomed publication of the letter – Assembly member and former national chairman Declan Kearney called it the most significant development in nationalist civic society since the hunger strikes.

Belfast lawyer Niall Murphy, one of the signatories, has taken some ownership of organising the letter, saying it came about through everyday conversations with other despairing nationalists.

Fellow signatory Brian Feeney, a writer and academic, revealed the letter was arranged last week after the DUP interrupted Brexit negotiations but before the UK-EU deal was reached.

This timing does not correspond neatly with Sinn Féin’s needs and behaviour – certainly not with the precision that might be expected. Republicans conspicuously pulled their punches over the off-and- on-again Brexit deal, the DUP’s influence in the interim and the British government’s weekend wobble.

Zero-sum game

Sinn Féin was definitely winning in the first half of this year, when it pulled down Stormont, triumphed in an Assembly election and consigned a traumatised DUP to the wilderness. June’s Westminster election and the DUP-Tory deal unexpectedly evened the score.

Now Brexit, the context behind Sinn Féin’s strategy, is starting to yield to political solutions in the party’s absence. This looks like losing – and the resulting unease and confusion naturally extends to the wider nationalist community, which gives Sinn Féin over 70 per cent of its vote.

Unionists are increasingly told they do not understand how angry nationalists are, how this has destroyed moderate acquiescence to the union and how it will trigger an imminent Border poll and Irish unification.

Yet for Sinn Féin, anger has reached its limit as a policy. Polls show the party’s support has peaked, while centrist Alliance and Green voters – the critical swing constituency– are dismayed by the suspension of Stormont.

In the end, nationalist anger only makes it harder for Sinn Féin to restore devolution, as it has known it must do since June’s election. So the communal frustration voiced in the letter is a double-edged sword, as is the very idea of a direct appeal to Dublin.

Drawing the Irish Government into a Northern crisis looked like a winning move in the first half of this year, enabling Sinn Féin to contrast its proactive momentum with Dublin’s diplomatic passivity.

Since June, on top of the new Tory-DUP dynamic, a new Taoiseach and Minister for Foreign Affairs, Simon Coveney, have become proactive in Northern Ireland, while Sinn Féin’s momentum has stalled.

Guarantee

Dublin’s tough stance on Brexit is the first cheering news Northern nationalists feel they have heard in years and they have responded with a striking mood of allegiance to the Republic.

The risk in this for Sinn Féin is that its supporters will go over its moribund head and look directly to Dublin – a development that would amount, in all-Ireland political terms, to cutting out the republican middle-man.

History shows that once Northern nationalists spy a more promising vehicle for their aspirations they switch to it rapidly. The prospect written between the lines of this week’s letter is of Sinn Féin sidelining itself.