IT BEGAN as an apparently sensible innovation to help Northern Ireland’s farmers and the environment in general. Yet the Renewable Heat Incentive (RHI) scheme wound up as a morass, which may cost almost £500m ($660m) of public money. It is also likely to make the task of restoring the region’s power-sharing government more difficult than ever.

RHI was based on a British scheme to encourage the use of wood-burning heaters on farms. But in Northern Ireland cost controls were omitted and subsidies were over-generous. This triggered a bonanza for claimants, with canny farmers, some connected to the government, christening it “burn to earn” and “cash for ash”. Warnings from whistleblowers and experts were ignored.

An inquiry into the scandal began in November, and this week heard evidence from Arlene Foster, leader of the Democratic Unionist Party (DUP), who launched the RHI in 2012 as enterprise minister. Mrs Foster has previously admitted not reading the legislation she introduced. This week she told the inquiry she was “accountable but not responsible” for what went on.

The episode has tarnished her party. One DUP official’s brother and two cousins acquired 11 boilers under RHI; the official admitted sending a confidential document on the scheme to a cousin. Another official claimed that a DUP minister on an official visit to New York was ejected from a bar after twice falling asleep, and was taken back to his hotel singing “Breakfast at Tiffany’s” at the top of his voice. The civil service has not come out of the affair well, either. David Sterling, its boss in Northern Ireland, admitted that some meetings had not been minuted, “on the basis that it is safer sometimes not to have a record” in case of freedom-of-information requests.

The inquiry has made nationalists no keener to revive the power-sharing arrangement with the DUP, which broke down in January 2017. It has also fuelled speculation about Mrs Foster’s future. But she has no ambitious rivals within her party. Nor is she likely to face much criticism from Theresa May, whose government is propped up by the DUP’s ten Westminster MPs. These factors may help her survive for now. Next year, with Brexit out of the way, Mrs May perhaps gone, and the inquiry due to report, she may come under pressure again.