Arlene Foster challenged by elderly claimants on her broken RHI promises

As part of the deal which saw Mrs Foster regain her position as first minister after three years out of office, the DUP leader agreed to a Sinn Fein request to shut RHI completely.

However, that means that many of those honest claimants who entered the scheme in good faith – and who already had seen their payments slashed from what they were promised would be unalterable 20-year subsidies – are under acute financial pressure and furious about those who urged them to join the scheme.

Already, subsidies in Northern Ireland have been slashed to a fraction of what is available in GB and in the Republic of Ireland.

Today the Assembly will discuss the closure of the scheme for the first time since the restoration of devolution.

However, the Sinn Fein motion which calls for the scheme to be shut will not in itself shut the scheme, something which will take some time and require legislation.

While Mrs Foster was the responsible minister, RHI was disastrously set up as a ‘burn to earn’ subsidy which provided an uncapped incentive for the use of biomass boilers which was higher than the cost of wood pellet fuel.

In January 2013, just weeks after the scheme had been launched, Mrs Foster wrote to Northern Ireland’s main banks to urge them to lend to potential RHI claimants.

She told them that RHI was set up to be “attractive to investors” and gave a person a cast-iron guarantee that the subsidies would never be cut.

Crucially, she said that tariffs were “grandfathered ... regardless of future reviews”, a legal term meaning that they are exempt from future legislative changes.

The letter also referred to a 12% rate of return, something which Mrs Foster subsequently said meant that she did not realise how wildly lucrative what was to become known as ‘cash for ash’ was.

Less than a fortnight ago – just days after Mrs Foster regained her job as first minister, something which Sinn Fein once promised it would never allow until she had cleared her name – she was sent an email by a north Antrim RHI claimant and his wife.

The individuals, who have spoken to the News Letter and whose identity has been confirmed by this newspaper but who asked not to be named, emailed Mrs Foster in response to her complaints that the government had broken its word to her over other issues.

In an email the couple said: “May I respectfully draw your attention to the disappointment you have expressed, as the prime minister and secretary of state have allegedly broken their promise regarding the finances available to the Northern Ireland government.

“We are likewise struggling with the financial disaster caused by your personal guarantee to the banks regarding the RHI repayments.

“We can no longer pay these and would appreciate your fulfilment of the above mentioned guarantee, especially as you are expecting no less from the British government.

“We look forward to your reply and are willing to make our bank details available to you, otherwise we have no viable solution to our financial difficulties.

“As you are expecting the government’s word to be honoured, so we have the same expectation of yourself. Anything else is hypocrisy!!”

Two days later, Mrs Foster replied to them, but essentially said “no comment”. She said: “As you are aware there is a public inquiry into matters surrounding the renewable heat incentive, which is still ongoing, and to which I have given evidence including around my letter to the banks which specifically referred to the rate of return of 12%.

“I have been legally advised that given that the inquiry has yet to report, that I am not to comment on any of these matters.

“After the select committee hearing at Westminster the Department for the Economy is now conducting a tariff review to deal with the issues raised.”

The DUP last night appeared to row back from the commitments to shut RHI which it signed up to in the New Decade, New Approach deal to restore Stormont.

The News Letter asked if the DUP leader had anything to say to the couple and to other people in similarly difficult financial situations. At the time of going to press there had been no response.

In response, the party said in a statement: “The parties in the Executive have not yet agreed a Programme for Government (PfG), the outline PfG contained within the document was published by HMG. The New Decade New Approach deal was published by the government after cross-party talks as a fair and balanced way forward.

“People entered RHI with good intentions. Those people must be treated fairly too. They should not be penalised as a result of no wrongdoing or mistakes on their part.”