Arlene Foster was minister when the RHI scheme was set up. Photo by Kelvin Boyes / Press Eye.

In a further example of how in the absence of ministers Stormont now appears to be more open in releasing previously withheld information, the Department for the Economy has released in full all of the documentation previously withheld.

The papers relate to a written Assembly question – two years before the catastrophic spike in ‘cash for ash’ applications – in which Green Party leader Steven Agnew asked Mrs Foster if she was concerned that subsidies for wood pellet boilers meant that people were not incentivised to conserve energy.

That September 2013 question, which touched on the perverse incentive at the core of the RHI scandal, was answered by Mrs Foster in a way which dismissed such concerns.

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Mrs Foster set out an assumption which it is now clear was incorrect. The then minister said that “within the existing RHI for commercial premises it is assumed that the installation of a biomass boiler, or another renewable technology, would be the final action taken by a business seeking to become ‘low-carbon’, with the costs involved in installing renewable heating much greater than those involved with simple energy efficiency measures”.

On 14 December the News Letter asked the department for all information which related to how that question was answered. The department did not respond within the legal maximum time frame of 20 working days.

However, the department – which since the election has been under the sole control of permanent secretary Andrew McCormick after DUP minister Simon Hamilton left post – has now released all of the information which it holds (with the exception of junior civil servants’ names).

The documentation shows no evidence that Mrs Foster raised any internal questions about what Mr Agnew had suggested.

Rather, the response was drafted by officials (as is the case with virtually every written question to ministers at Stormont or Westminster) and then rubber-stamped by Mrs Foster – along with 24 other written responses to separate Assembly questions, none of which were altered in any way.

The documentation also raises questions for officials in the energy division at what was then the Department of Enterprise, Trade and Investment (DETI) because it shows that it was they who provided the detailed draft answer which Mrs Foster rubber-stamped.

The draft response was prepared by Fiona Hepper, one of the key officials involved in setting up the RHI scheme. She has since been promoted to be a deputy permanent secretary at the Department of Education.

In background briefing given to Mrs Foster by officials, she was told “the demand for biomass is already encouraging Invest NI companies to invest in R+D and new product development....with clear export potential.”

On October 7 an email said that “the minister has cleared the following [written Assembly questions] without amendment”.

By the stage that she rubber-stamped the answer to Mr Agnew’s question, the lack of cost controls or allegations of abuse had been raised with Mrs Foster by consultants in June 2013, by officials in the July 2013 consultation document and by the whistle-blower in September 2013.

The News Letter asked the DUP why, given her cumulative level of knowledge, Mrs Foster did not take the issue more seriously and ask questions at that point or subsequently. The party had not responded at the time of going to press.

In January, Mr Agnew had himself asked for the same information. The department replied the following month to confirm that it held the information but that it was being withheld. It argued that it was doing so because it was necessary to “protect the private thinking space necessary to seek advice and discuss and debate issues free from external scrutiny when required”. Ministers are responsible for signing off on every FoI request.

Last night Mr Agnew said it was “of great concern that as an elected representative I have been denied access to information that has since been supplied to a journalist.

“I can only conclude that political interference by the then Minister Simon Hamilton resulted in my request being rejected.

“This is an example of a deliberate attempt to deny transparency in government decision making and is further evidence of the need for the public inquiry to establish the full facts of the cash for ash scandal.”

He added: “The fact that Arlene Foster signed off on this response without any interrogation of the issue is symptomatic of a minister who was not on top of her brief.”