Arlene Foster has blamed her officials for the RHI scheme's flaws

Referring to the regulations then being devised by her civil servants, the then enterprise minister said: “I have made clear plans for a Renewable Heat Incentive (RHI) for Northern Ireland.”

However, over recent weeks Mrs Foster has repeatedly blamed her civil servants for the failures of the scheme – such as the decision to strip out the cost controls which were present in the GB RHI scheme, even though about 98% of the other GB regulations were simply copied and pasted across.

At a recent meeting of the Public Accounts Committee, senior civil servant Andrew McCormick made clear that civil servants had failed their ministers in both the drafting of the regulations and in how they were implemented. Dr McCormick profusely apologised for those civil service failings.

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However, he said that it was not his place to comment on the competence of ministers.

Mrs Foster’s comments were made in a foreword to a niche publication, the 2012 Energy Institute Yearbook and Directory for Northern Ireland, which has been uncovered by the News Letter.

Writing in the yearbook, Mrs Foster took personal credit for the setting up of the RHI.

She said: “The over reliance on fossil fuels is perhaps most evident within the local heating market where less than 2% of demand is satisfied from renewable sources.

“We have therefore set a target of 10% renewable heat by 2020 and in order to achieve this level I have made clear plans for a Renewable Heat Incentive (RHI) for Northern Ireland.”

Mrs Foster also demonstrated personal knowledge of the budgetary aspects of the scheme during the period in which it was being designed.

She said: “My department is currently finalising the design of the RHI scheme in advance of implementation.

“The scheme initially represents funding of £25m, however over the entire lifetime of the RHI the actual support levels will be much higher.”

The latter comment could refer to the fact that the scheme was to run over 20 years and mean that Mrs Foster was simply referring to the fact that the £25 million only covered the first few years of the scheme.

But it could allude to a deeper misunderstanding of the scheme’s financial basis which appears to have been prevalent within the department whereby they believed that Westminster would pick up the tab for the scheme regardless of how many people piled in to take advantage of the lucrative rates on offer.

The News Letter asked the DUP whether the indication of her personal knowledge of the RHI budgetary situation indicated that Mrs Foster knew the costs would be astronomically higher because of the removal of cost controls, but believed the funding was coming from the Treasury.

We also asked how Mrs Foster could take credit for the work of her officials in setting up the RHI but now blame those same officials when it goes wrong.

The DUP did not respond to either question.