For the last decade, political stability in Northern Ireland has depended on the maintenance of a delicate equilibrium between unionism and nationalism.
Ever since the DUP and Sinn Fein took over as power-sharing partners in 2007, governance from Stormont has been a careful sharing of the spoils.
As well as their shared efforts in areas such as health and economic development, the DUP trumpeted what it has done to help Orange Halls while Sinn Fein publicised what it has done for GAA clubs.
Each party knew that not only did it have to get something out of the arrangement, but the other had to as well.
Over the last year that equilibrium was fundamentally upset. A combination of DUP over-confidence (or in cases, the hubris which comes from 15 years of political dominance) and Sinn Fein complacency led to a belief within nationalism that they were not getting a fair deal from Stormont.
As Sinn Fein’s vote plateaued and then fell in last year’s Assembly election, the party failed to appreciate the scale of the festering grievance and instead formed an even closer relationship with the DUP, to the extent that they appointed a joint spokesman to sell what would be their joint message.
The RHI scandal in December made the simmering resentment a full-blown crisis for Sinn Fein. The party’s initial instinct was to smooth over the problem by holding a behind-closed-doors investigation and keeping its relationship with the DUP intact.
But the scale of public - and particularly nationalist - anger ultimately led Sinn Fein to collapse Stormont in January.
Fast forward to March’s election and the equilibrium shifted radically in the other direction: in a slightly smaller Assembly, unionism lost 16 seats while nationalism lost just one.
Since then, a reinvigorated Sinn Fein has refused to re-enter power-sharing without major concessions by the DUP. The DUP has publicly and privately made explicit its willingness to take some pain by making concessions in those talks. But, given its exceptionally strong hand, Sinn Fein has given no indication that it is prepared to meet the DUP half-way.
A General Election has now intervened and that brings risks for all the parties. After the election, the two big parties have 21 days in which to agree a deal.
The chances of that happening are likely to be enhanced if this election swings back somewhat in unionism’s favour, restoring something of the equilibrium which once existed.
On the other hand, if Sinn Fein obliterates the SDLP and essentially is rewarded by the nationalist electorate for its hardline stance on re-entering Stormont, the restoration of power-sharing would seem to be far less likely.
In that scenario, Sinn Fein would have a mandate for its tough position - making compromise potentially problematic to sell to those voters - while a weakened DUP would not be in a position of strength from which to make a lasting deal.
But whatever the outcome of the election, there are major risks building for Sinn Fein.
If Gerry Adams and Michelle O’Neill refuse to re-enter Stormont by the end of this month, direct rule from London – in whichever format that comes – is inescapable.
There appears to be a split in republican thinking between those who believe that any chance to move power from London to the island of Ireland should be grasped (Sinn Fein’s stance for almost 20 years) and those who, thinking strategically about how support for a united Ireland can be built, believe that a period of unpopular Tory rule from London while Brexit is unfolding could destabilise Northern Ireland in their favour.
Whichever of those arguments prevails, we have this week received an insight into how London rule is likely to unfold.
Unusually, given the low levels of support for the Tories in Northern Ireland, the Conservative Party’s Northern Ireland manifesto is arguably the most important of the manifestos in this election because as things stand it is the most likely to be implemented.
Strikingly, the 34-page document is more detailed than some other manifestos – notably, Sinn Fein’s, which contains just two firm pledges. That may indicate that in recent months the Tories have been thinking about what they would do if Stormont cannot be resurrected in the short term.
The document was drawn up by CCHQ, rather than by the NI Conservatives.
I understand that the main author of the manifesto was Lord Caine, the veteran special adviser to successive Tory Secretaries of State since 1991 who stepped down from that role to return to London for the election campaign, with significant input from the Secretary of State. After that, the manifesto was signed off by Cabinet Office minister Ben Gummer and then by Theresa May’s powerful chiefs of staff, Nick Timothy and Fiona Hill.
It sets out some of Theresa May’s central ideas (“we do not believe in untrammelled free markets; we reject the cult of selfish individualism”) as well as classically Conservative ideas on taxation, the welfare state and defence.
But some of the most striking passages are those in which the party espouses its unionism – and the implications of its unionism, such as the explicit rejection of joint London-Dublin authority over Northern Ireland, as the SDLP has called for. That suggests a future Government (presuming that Mrs May wins the election) which will be unusually and explicitly pro-Union.
Yesterday the DUP’s Nigel Dodds made the point that even if Mrs May has a majority of 50 or 60, it could be negated in key votes by 25 or 30 rebels.
Then, in a revealing insight – at least into how the DUP perceives its national clout – he went on: “The DUP’s influence at Westminster doesn’t just depend on the arithmetic. It depends on the networking influence that we have developed, the relationships that we have developed that continues, whether there’s a tight Parliament or a strong Tory majority.
“We have proved that – you only have to look at some of the statements in the Conservative manifesto to see the influence, the pro-Union influence that there’s been in terms of our work at Westminster and in recent years.”
It is almost certainly the case that in the Brexit negotiations, the preeminent work of the next Government, the Government will need the Irish Republic’s help and, if the price of that help is concessions on Northern Ireland, that could override the manifesto commitments.
It is also the case that Conservative unionism does not necessarily cherish the cultural trappings of Ulster unionism which motivate so many within the DUP. There is, for instance, no mention of parading in the manifesto.
But, regardless of the local outcome of the election, if direct rule is on the horizon that is likely to shift the political balance back in favour of unionism. The question is whether, if that comes, it will be after another electoral disaster – or a reversal in fortunes.