The final straw came when it emerged that a green-energy initiative she organised as enterprise minister in 2012 would cost breathtaking sums of money. Businesses received large subsidies to keep wood-fired boilers going—even to heat empty sheds—in what has been dubbed the “cash for ash” or “burn to earn” affair. The scheme could eventually cost the region £490m ($600m). Mrs Foster initially said she could not be expected to scrutinise “every single jot and tittle” in her department. But later she admitted there had been “a catalogue of mistakes”. She has accepted that an investigation should go ahead, but maintains she did no wrong and thus need not stand aside. Facing a barrage of criticism, she declared: “There’s a lot of it personal…a lot of it, sadly, misogynistic as well.”

Voters may soon get the chance to deliver their own verdict. Mr McGuinness’s resignation as deputy first minister has brought the operation of Belfast’s devolved administration to a shuddering halt, since its rules demand that it be jointly headed by a unionist and a republican. The British government is holding talks to patch things up between Sinn Fein and the DUP. If those efforts fail—as most believe they will—a new election is on the cards.

Such a contest would be “brutal”, Mrs Foster has said. Both the DUP and Sinn Fein would face challenges from smaller opposition parties. But in Northern Ireland, where old voting habits die hard, the DUP and Sinn Fein would be favourites to emerge again as the main forces. The number of seats in the Assembly at Stormont is due to fall from 108 to 90 in a cost-saving exercise. Small parties are likely to lose out.

Whatever the outcome of any election or inquiry, republicans are already insisting that they will not agree to a return to the politics of the past year, which they say exposed Mrs Foster’s opposition to the principle of “parity of esteem” in which the parties are supposed to hold each other. In recent years there have been signs of deepening disillusion with the Assembly in the republican strongholds of Belfast and south Armagh. Although Sinn Fein leaders, among them Mr McGuinness, have been willing to keep trying in the Assembly, many at the grassroots have concluded that Stormont is a waste of time.

A key moment came in December when one of Mrs Foster’s ministers cut £50,000 in funding for teaching the Irish language, which republicans regard as a touchstone issue. A curt e-mail to teachers announced: “Because of efficiency savings, the department will not be providing the Liofa bursary scheme in 2017. Happy Christmas and Happy New Year.” On January 12th the move was reversed, but by then the damage had been done.

As the government in London works to steady Northern Ireland’s political settlement with one hand, it is rocking it with the other. The vote last year to leave the European Union—in which the Northern Irish voted to remain—presents several problems. The Good Friday Agreement of 1998, which established Northern Ireland’s devolved government, was signed on the assumption of Britain and Ireland’s shared EU membership. The Supreme Court is currently considering whether Northern Ireland’s Assembly should therefore be consulted before the government can trigger Article 50, the legal route to Brexit. If the court rules in favour, elections in Northern Ireland could delay the process.

Nor does anyone in London yet have a good answer to the question of what will happen to the open border with Ireland in the event that the United Kingdom opts out of the free movement of people to and from the EU (see article). A harder border, including checks on people and goods, could rattle both Northern Ireland’s economy and its political settlement.

It would be a bad time to lose Mr McGuinness from politics. He will not say what explains his sudden poor health, nor whether he will fight the next election. During ten years as deputy first minister his authority and charisma have been valuable in assuring republicans that it is worth keeping Stormont going. And he has built bridges with unionists, too. Talking to the queen last year he asked about her health and she was overheard replying: “Well, I’m still alive anyway.” His friendly relationship with the queen, a second cousin of whom was murdered four decades ago by the IRA, shows how far things have come—and how much is at stake.