I've lost count of the number of Northern Ireland media commentators who regularly and spontaneously burst into laughter at the mere mention of Peter Robinson's "graduated unionist response" promised over the parading stand off over the Ardoyne shops in North Belfast.

Flicking through the pages of Belfast newspapers on Saturday morning, there was little laughter and few explanations as to how, for example, Nigel Dodds managed to effect a full 7pc bounce in the Unionist vote.

Undoubtedly Sinn Féin's refusal (or inability, it is never quite clear which) to broker an accommodation to enable a very small number of Orangemen to walk home past the Ardoyne shops every 12th of July has acted as fuel to a Unionist electoral bonfire.

Latterly, the loyalist frustration over that stand-off has been channelled into voter registration. DUP activists in the area say that, after years of voter apathy, the banning of the return parade triggered an enthusiasm for voting they've never seen before.

And not just in Belfast. Proportionately, the Unionist vote is up all across Northern Ireland, and the Nationalist vote universally down. It was not supposed to happen like this.

Sinn Féin has long subsisted on a political fantasy that the continued rise in the Catholic birth rate makes it likely that most Catholics could then be corralled into a single United Ireland lobby.

This is also undermined by the rising vote for the cross-community Alliance party and the Greens.

The knock-on effect was evident as far away as Fermanagh-South Tyrone, where Sinn Fein's attempts to bully and cajole the SDLP into a counter-unionist pact failed, and as a result it lost a seat Michelle Gildernew (inset) had held for 14 years.

For Sinn Féin strategists - now largely headquartered in Dublin - this is no longer a laughing matter.

In one election result, the party's 'inevitability myth' has taken a hit. And a very palpable one.

If you discount the votes gathered by Mairtin O'Muilleoir in South Belfast, where the party did not run a candidate last time, for the first time since the Good Friday Agreement Sinn Fein's overall vote total dropped, albeit very slightly.

In Gerry Adams's old fiefdom, in West Belfast, Paul Maskey's vote dropped 16pc from the previous by-election. That's the worst Sinn Féin performance in West Belfast since 1996.

The slack was largely taken up by the People Against Profit candidate Gerry Carroll whose performance, if replicated in next year's Assembly election, would see Sinn Féin lose one of its five seats there.

The loss of a seat is much less worrying for Sinn Féin than the prospect of losing it to a party which also organises north and south on the same anti-austerity agenda Sinn Féin has been trying to make its own in the Republic.

Having first agreed on a wide programme of cuts in public sector jobs and a concession from Westminster on slashing Corporation Tax, Sinn Féin belatedly reneged on the Stormont House Agreement, in hopes of a putative Labour government granting further concessions.

It was a reckless gamble it may have cause to regret.

Now Sinn Féin faces the prospect of facing down not only other parties within the Executive, but a UK government which has shifted substantially to the right and has a plan for implementing far more savage cuts than anything contemplated by the outgoing coalition.

In West Belfast, where Sinn Féin has enjoyed Scottish Labour levels of political dominance, child poverty is second highest over all UK parliamentary constituencies.

Weakened political opposition has allowed SF to flip seamlessly from playing the role of government benefactor to angry opposition and back again, as and when it has been politically convenient. But that appears to have ceased providing its usual pay-offs.

There's no clear evidence that the party's long policy of not taking its seats contributed to the dulling of the nationalist electoral, but growing numbers of younger nationalist voters are publicly asking why they should vote for representatives who won't do the work of an MP on principle.

The comparison with the DUP, whose electoral focus on building Northern Ireland's influence in a tight Westminster parliament is, to say the least, unflattering.

Even if Gerry Kelly's last minute appeal to all Catholics to vote for him to get the Protestant Nigel Dodds out was merely speaking to the core reality of sectarian north Belfast, people do not like being told that that is all they are voting for.

The problem with populism is that it can make you unpopular particularly if, like Sinn Féin, you have had senior control of government levers for the last eight years and have little to show for it but the frustration of a few marginalised north Belfast Orangemen.

These poor results did not spring out of nowhere. Electorally, the drift has masked by marginal gains at the expense of the SDLP, and the big push in the south.

In truth Sinn Féin has been wandering around a plateau in Northern Ireland for some time now without any sign of a political roadmap.

Up until now it has relied on cowed opposition from the SDLP, and stoking tribal fears of political unionism.

But the lack of competition has ill served nationalism, whose turnout is now falling, in contrast with the crowded political market in unionism.

Mick Fealty is a blogger and communications consultant and founding editor of the Northern Ireland-based blog Slugger O'Toole

Irish Independent