Arlene Foster was set to chalk up her first 12 months in charge of Northern Ireland today but that milestone has now been cut short by her own appalling hubris.

For the uninitiated, the First Minister introduced a renewable energy subsidy in 2012 that was so botched it is predicted to saddle Northern Ireland with a £500m liability.

The failure to establish cost controls in the Renewable Heating Incentive programme – a grant for businesses and farmers switching to wood pellet-burning boilers – which Foster introduced in her previous role as enterprise minister – should be a clear-cut resignation issue.

But Foster thinks she is subject to a higher burden of proof.

So instead of contrition, she is a picture of snarling defiance, refusing to step aside while an independent investigation takes place into the scandal.

And, so, there was a grim inevitability about Martin McGuinness’s resignation as deputy First Minister of Northern Ireland this week, precipitating, as it does under the terms of the Good Friday Agreement, fresh elections to the Northern Ireland Assembly.

Theoretically, there is a seven-day cooling off period. But the mood is sour. Elections are priced-in.

Although Sinn Féin had absolutely no interest in trying to oust her, preferring to keep Northern Ireland’s show on the road if at all possible, Foster’s unbearable arrogance in recent weeks simply made matters untenable.

In essence, McGuinness fell on Foster’s sword for her in order to bring this issue to a head. The situation had become a parody of democratic accountability and someone had to insert some dignity back into proceedings.

So now the Democratic Unionist Party will be left explaining this mess to voters on the doorstep. With Foster’s plunging approval ratings, their candidates may end up wishing they had sacrificed her for their own self-preservation.

Indeed, the smart move would have seen the "men in grey suits" pay her a visit and urge her step down when this scandal broke before Christmas, in order to avert fresh elections and prevent any further damage to power-sharing.

At the heart of it, though, this is merely a case of her garden-variety ministerial incompetence, assiduously reported by Northern Ireland’s excellent local media.

Alas, Whitehall has not been as on the ball these past few weeks.

Before he issued a short statement on Monday night promising to do "all that we can to help the parties find a resolution in the coming days", Northern Ireland Secretary, James Brokenshire’s last public utterance was on December 15 and he appears to have made no public intervention to avert this slow motion pile-up.

Yesterday, he told the House of Commons that he backed calls for a "comprehensive, transparent and impartial inquiry". If made last week, his intervention could have perhaps tipped the balance back towards political reason.

Last night, however, the leader of the cross-community Alliance Party, Naomi Long, suggested Westminster game-playing might lie behind the government’s lethargic response.

"There is a growing perception in Northern Ireland that the potential usefulness of DUP votes in Westminster to advance Brexit may be compromising the UK government’s willingness to challenge the DUP and ability to act as honest broker and impartial guardians of the Good Friday Agreement," she claimed to The Independent.

She also confirmed that she had written to Theresa May twice over the past month, warning about the potential collapse of the executive. To no avail.

Apart from the eye-watering amounts of public money that have been squandered, this mess is also significant because it exposes the basic lack of trust and mutual respect at the heart of devolution in Northern Ireland.

The price of power-sharing between parties that have such diametrically-opposed beliefs is that the executive operates in silos, so the scale of the mess surrounding the RHI scheme didn’t come to light earlier.

But that is now academic. Tempers are raised on all sides, with Sinn Féin mightily aggrieved by Foster’s sheer pig-headedness, while the DUP are busy circling their wagons in response to criticism. It may be harder to put all this back together than it seems.

There are also a series of notable ironies.

It was Foster’s successor as enterprise minister, her DUP colleague Jonathan Bell, who blew the whistle on the Renewable Heat Incentive (RHI) scandal, claiming that although his political career would be ‘finished’ as a result, ‘God doesn’t punish people who tell the truth’.

The row also pits Sinn Féin as custodians of the British public purse while the DUP’s basic lack of financial rectitude, while playing fast and loose with the rules, is more reminiscent of a southern Irish political scandal.

As for Foster, she managed to heap schaudenfraude onto hubris in her response to McGuinness’s resignation, claiming that it prevented swift action being taken to tackle the RHI mess.

‘His actions [McGuinness] have meant that, at precisely the time we need our Government to be active, we will have no government and no way to resolve the RHI problems,’ she actually had the chutzpah to claim.

At any other time, these elections might have been a useful proxy to gauge reaction to Brexit, but this is now a referendum on Arlene Foster. Watch to see if the Ulster Unionists and Traditional Unionist Voice now benefit at the DUP’s expense in the various intra-unionist electoral battles.

Lastly, there was a valedictory tone to Martin McGuinness’s resignation letter.

It is on the record that he is receiving medical treatment for a, as yet, unconfirmed illness. It is far from clear at this stage whether he is coming back to the frontline.

This should give pause for thought given his presence in the power-sharing executive has been pivotal for the past decade. His letter said, with a hint of regret, that he had always "sought to maximise the potential of the institutions for forward progress in a society emerging from bitter conflict".

The bottom line is this mess was utterly avoidable. Amid the confusion and uncertainty about what happens next, one thing is clear. Voters should hold Arlene Isabel Foster to account for her willingness to lay down Northern Ireland’s assembly for her own political life.

Kevin Meagher was former special adviser to the last Labour Government’s Northern Ireland Secretary, Shaun Woodward and author of ‘A United Ireland: Why unification is inevitable and how it will come about,’ published by Biteback.