Thanks for joining us for a fairly full-on day at the RHI Inquiry.

Tomorrow, we'll hear opening statements from the inquiry's core participants - the Department for the Economy, the Department of Finance, and Ofgem, which administered the RHI scheme.

The sitting will kick off at 12:30 GMT, so join us then!

BBC News Northern Ireland

DUP special advisers worked to stop decisions being taken about the RHI scheme as it came under huge budget pressure, the inquiry into the botched energy initiative heard.

It was also told that one adviser - Andrew Crawford - was able to predict the spike in applications that led to the £700m overspend, and he shared internal emails with family members, one of whom later benefitted from the scheme.

And a businesswoman who flagged up big problems in the project was a "persistent voice of warning" in the ear of the department responsible for running it.

Senior counsel David Scoffield QC finishes his lengthy opening statement, saying he hopes it provides a "helpful insight" into what is to come in the RHI Inquiry over the next several months.

Image source, RHI Inquiry

Inquiry chair Sir Patrick Coghlin praises Mr Scoffield for his work, saying the panel has "benefitted greatly from the detail and care" of his address.

The inquiry hears that in December 2015 Dr Andrew McCormick and Timothy Cairns discussed their conversation about the potential delay to the assembly debate and their recollections of it differed.

Mr Cairns said he did not make the reference to Fermanagh (below) businesses not having time to apply to the RHI scheme, and Dr McCormick accepted that his own recollection was "imprecise".

Mrs Foster has told the inquiry that she raised the issue with Mr Cairns on behalf of a constituent.

She added that when she was told about the cost implications she accepted that the plan to implement the cost-cutting measures should go ahead without delay.

That "episode" will be probed by the inquiry, Mr Scoffield says.

Another "potentially significant" event in the delay in implementing cost controls during the spike period is raised by Mr Scoffield.

In his evidence to the inquiry, Dr Andrew McCormick says that he was asked by DUP adviser Timothy Cairns if it was possible for a delay of about "a week or so" in the Northern Ireland Assembly debate on the changes to the scheme that would have made it less lucrative.

Image source, AFP

He believes that Mr Cairns referred to a concern that "not enough businesses in Fermanagh had been able to apply" before the curbs would be put in place.

Dr McCormick said that he felt that call was being made on behalf of the DUP leader Arlene Foster, an MLA for Fermanagh and South Tyrone.

According to his testimony, he asked DETI officials if a delay would be possible and was told that putting it of by just one week would result in a cost of £2.6m a year over 20 years.

"At least some" of the leak of information about the impending cost controls came from a DUP adviser, says Mr Scoffield.

As mentioned earlier, Andrew Crawford had forwarded a July 2015 email, detailing the proposals in a ministerial statement, to his personal account.

Image source, Getty Images

Mr Scoffield shows the inquiry that Mr Crawford then sent it to one of his relatives, Richard Crawford.

A couple of months later, Richard Crawford had a number of boilers approved on the RHI scheme.

Another was forwarded by Mr Crawford to another prospective applicant, who the inquiry believes is also a relative, but it appears that person did not avail of the scheme.

Mr Scoffield says it is clear that, from early July, DETI civil servants "were in open discussion with the heating and farming industries about the details of the proposed changes".

He says the department's submission "suggests that there should have been a greater appreciation of the potential impact of providing advanced notice to stakeholders".

Image source, Getty Images

Mr Scoffield says a number of civil servants have "mounted a spirited defence" of their interaction with the industry in the summer of 2015.

For example, Stuart Wightman of DETI's energy division says in his submission that he was consulting with the industry to inform it of the policy proposals and "my subsequent advice to the minister in line with the Northern Ireland Executive's 'A Practical Guide to Policymaking in Northern Ireland'".

Information about changes to the scheme that would make it less lucrative were circulating to the heating industry and potential RHI scheme applicants well in advance of their implementation, says Mr Scoffield.

"It now seems clear that the word was out," he says.

Image source, Getty Images

DETI officials themselves had revealed those details and made "little attempt to conceal or disguise what was going on".

He refers to emails on 1 July 2015 between energy firms, in which they discuss the impending changes, saying they have received the details directly from the department.

Those emails were being exchanged between the firms before the proposals for cost controls had even been submitted to the DETI minister.

A huge spike in applications to the RHI scheme between the end of August 2015, when the cost control measures were agreed, and mid-November that year, when they were finally implemented, was the main reason for the huge projected overspend, which sits at £700m.

Up to August that year, 818 applications had been received since the scheme's inception in 2012.

Image source, Getty Images

After the changes were announced on 8 September there were 957 applications.

In a single week in October, 200 applications were received - more than the total submitted in the first 19 months of the initiative.

Mr Scoffield discusses the status of special advisers, explaining that they are appointed as temporary civil servants and must adhere to a code of conduct.

Image source, RHI Inquiry

Mr Scoffield says conflicts of interest would appear to come under paragraph five of the code.

"They should not misuse their official position or information acquired in the course of their official duties to further their private interests, or the private interests of others," he quotes.

DUP adviser Andrew Crawford has told the inquiry that he has no memory of discussions about the RHI scheme with his relatives who claim from it.

He said he forwarded the emails from fellow DUP adviser Timothy Cairns, about proposed cost controls in the scheme, to his personal account - those were mentioned earlier - so he could view them on an iPad.

Image source, Getty Images

He believes he may have shared the information - including the amendment plans - with people who were aware of the scheme, but says they were already well versed about it.

Mr Scoffield says Mr Crawford met a boiler installer and the major poultry producer Moy Park but he did not promote the scheme.

Mr Scoffield turns to the matter of a delay in the introduction of changes to the regulations from 1 October to 4 November, decided at a meeting of 24 August 2015.

He says that the then DETI permanent secretary Dr Andrew McCormick "feels that was because Mr Cairns asked for a delay beyond 1 October, but also that Mr Cairns did so under the influence of others".

Image source, RHI Inquiry

In his evidence, Mr Cairns "accepts that he was seeking to delay the introduction of cost controls for as long, but no longer as the civil servants would accept", says Mr Scoffield.

He adds that Mr Cairns expresses surprise that the officials agreed to put the introduction of tiering back over a month.

"Every additional week" of delay in acting on the proposals to add cost controls to the RHI scheme "caused significant additional financial pressure" on DETI, says Mr Scoffield.

He says that the ministerial adviser Timothy Cairns may have been "stalling in dealing with the submission" and he had not passed it on to the then DETI minister Jonathan Bell (below).

There is "no sense" that Mr Cairns was "acting with any degree of urgency", while civil servants were growing increasingly nervous about the state of the scheme.

There is also little sense that Mr Bell had any involvement in the issue until late-August, adds Mr Scoffield.

In an email at the end of July 2015, Andrew Crawford (below) tells Timothy Cairns that he believes DETI will "need to make changes" to the RHI scheme from 1 October.

He goes on to say that the initiative "pays (poultry) producers to heat houses when their houses are empty".

Mr Crawford has made the case to the inquiry that the expression of his view that changes were needed in the scheme shows that he was not trying to delay the proposed introduction of cost controls.

But Mr Scoffield says there is a "strong prima facie case" that Mr Crawford's suggestion would "soften" the change from what was proposed.

Mr Scoffield says that Mr Crawford "does seem to be aware" that there was a burn-to-earn benefit from the scheme.

Mr Crawford has been asked by the inquiry when he first became aware of the profit-making potential of the scheme - he has said he "cannot recall".

Mr Scoffield refers to an email from Andrew Crawford to Timothy Cairns sent on 20 July 2015.

He says this is "an interesting email for a number of reasons", one being that Mr Crawford "is able to predict the spike (in applications) it seems, which later transpires".

In the email, Mr Crawford says: "The word on the street is there are going to be changes made in October and you are going to get a massive spike in applicants before that date."

Mr Scoffield says the inquiry "will want to look at how the word on the street was out already".

Emails the inquiry has obtained show that the July 2015 submission regarding the RHI cost controls was sent by the DETI minister's adviser Timothy Cairns to two fellow DUP advisers.

They were Stephen Brimstone (below), who was at the Office of the First Minister and deputy First Minster (OFMDFM), and Andrew Crawford, who was at the Department for Finance and Personnel (DFP), advising the then finance minister Arlene Foster.

In the email, Mr Cairns writes: "Stephen, Andrew - attached is the latest on the Renewable Heat initiative for your info and input."

Mr Crawford forwarded the email from his civil service account to his own personal account.

There is a "real issue" about when Mr Bell got to see the submission, says Mr Scoffield - the minister had been away for parts of July and August - but it is "not at all clear" from the evidence seen to date as to when he received it.

The inquiry's dig for evidence on that issue is still going on, Mr Scoffield says.

He acknowledges that this part of the scandal is "politically contentious" and there are "differing versions" about what happened in the summer and early-autumn of 2015 as given by the "key players" at the time.

Details of a "key" submission to Mr Bell in July 2015 urging the introduction of cost controls in the scheme are outlined by Mr Scoffield.

It was marked as "urgent" but it took weeks to be acted on - final approval was not given until 3 September and the measures to add cost controls suggested in it did not take effect until November.

Image source, Getty Images

A major spike in applications that led to the scheme's massive £700m overspend occurred during that delay.

In its evidence to the inquiry, Mr Scoffield says the Department for the Economy makes a "significant understatement" in saying that the submission was "not approved immediately".

Having broken for lunch, Mr Scoffield picks up for the afternoon session.

He says that Mr Bell expresses a number of concerns in his evidence to the inquiry about the actions of his permanent secretary at DETI, Dr Andrew McCormick.

"Mr Bell contends that in August to September 2015, the issue of RHI was raised but no specifics were provided in relation to the overspend," Mr Scoffield says.

Image source, RHI Inquiry

Dr McCormick has also provided a number of lengthy submissions to the inquiry, Mr Scoffield explains.

He says that, while they do not entirely support the minister's complaints about his adviser, they make it clear that "the relationship between messrs Bell and Cairns was at times volatile".

Dr McCormick's submissions describe tensions in the DUP's ministerial and special adviser teams amounting to "a breakdown in trust" that "created an additional challenge for the officials".

Mr Bell has also claimed that Mr Cairns was given instructions from other DUP officers or advisers.

When concern was raised by Dr McCormick in the summer of 2015 about the issues with the scheme, Mr Bell claims that his advisers said he "did not wish it to be on the agenda" at the behest of other DUP advisers.

According to Mr Scoffield, he also says there was a "concerted attempt" to delay action in the scheme by keeping it off the agenda.

Mr Bell has told the inquiry that his adviser was acting under the influence of then DUP advisers Andrew Crawford and Timothy Johnston (above left, pictured with the then DUP leader and first minister Peter Robinson).

The same claims were made by Mr Bell in his interview with the BBC last year, and the DUP advisers denied them.