Mr Aiken brings up the matter of an email exchange between Dr Crawford and David Dobbin of United Dairy Farmers in December 2014.

He says this is another example of the forwarding of information outside the department.

Mr Dobbin was due to take part in a BBC interview on energy matters.

Dr Crawford agreed to send him a briefing.

Image source, RHI Inquiry

He subsequently sent Mr Dobbin draft DETI answers to BBC questions.

"Should you have done that?" asks Mr Aiken.

Dr Crawford says he doesn't see anything wrong with it.

Dr MacLean (above) suggests that Mr Dobbin's interests may not have been shared with those of the department

"It was up to him to decide how to answer the questions himself," says Dr Crawford.

Mr Aiken puts it to the witness that december 2014 was "a significant missed opportunity to have in place the cost control mechanism that had been consulted on".

Dr Crawford accepts "it would have been good" to introduce the controls at that point.

Image source, RHI Inquiry

In hindsight, Sir Patrick says, Dr Crawford should have advised Mrs Foster that, as a matter of protection, she should have taken the decision to decouple the schemes herself.

"The problem with hindsight is whether or not... had they appreciated that all of this might have been different," he says.

Panel member Dr Keith MacLean takes up the questioning now.

He observes that Dr Crawford has been critical of DETI officials and wonders whether the structures surrounding the role of a special adviser (SPAD) were lacking.

The witness says it was the onus of the department to ensure that their internal checks and balances provide correct information to the minister.

Dr MacLean asks Dr Crawford whether it is "impossible for a SPAD to protect the minister?".

Image source, RHI Inquiry

"This was not an isolated incident... what came from officials was wrong and incomplete," says Dr MacLean.

Dr Crawford repeats that he does not believe the role of a SPAD was to check the accuracy of specialist energy reports.

Dr MacLean makes the point that Mrs Foster claimed she expected Dr Crawford to have read these reports.

Dr Crawford says it is a question that needs to be put to Mrs Foster.

Sir Patrick continues asking Dr Crawford on the omission of cost controls.

He asks the witness why he failed to check whether the measures in the public consultation were included in the December 2014 submission.

"I simply did not have time to be checking officials homework," says Dr Crawford.

"I did not expect to be ensuring that officials put in documents a true reflection of what had gone out in the consultation document before that. I did not have the time to do that. I was there to give political advice."

Image source, Getty Images

Sir Patrick has one final word on this topic:

"I’m not going to press this any further, you’ll probably be glad to hear, but only to say this: It is not a question of checking officials homework. It’s a question of being aware of a public consultation, what was contained in that consultation document that the public were told going happen and why as a matter of common sense that was not reconciled with that document."

Image source, Getty Images

Sir Patrick continues with his tough questioning.

"Is it not the purpose of a special adviser to protect the minister?" he asks.

Dr Crawford says he did his best to protect the minister, but "at the same time it was 800 civil servants in the department. I don’t believe I could have been expected over what every civil servant was doing".

"Looking here with hindsight yes, of course I should have seen it," says Dr Crawford.

Sir Patrick responds: "Dr Crawford you don’t need hindsight to see that two documents produced within a very short space of time from each other are contradictory."

Dr Crawford criticises the briefing document provided to Mrs Foster.

"Greater clarity should have been provided to the minister, and ultimately the minister through the statement in the chamber, to the public about the second stage of the scheme and the cost controls being brought in during that second stage," he says.

But Sir Patrick (below) argues point with him, saying was it not his responsibility to ensure that cost controls were included in the submission.

Image source, RHI Inquiry

Dr Crawford defends himself. He says it was his job to give political advice across a whole range of issues and he expected the officials dealing with RHI to have dealt with cost controls in the statement given to the minister.

"I don’t think it’s fair for me to be over every issue and the political detail of it all the way the officials were over the details," says Dr Crawford.

In 2013, a public consultation was held on phase two of the domestic and non-domestic scheme.

The consultation document said that cost controls would be applied to both schemes.

Officials subsequently decided to "decouple" the two schemes in order to prioritise the introduction of the domestic scheme, and the need for cost controls somehow no longer featured.

Image source, RHI Inquiry

Dr Crawford accepts that the decision to decouple should have been taken by the minister.

Inquiry chair Sir Patrick Coghlin says that a member of the public might well say:

"I'm now being told that one of these schemes is coming forward separately, and there's no reference here to cost controls."

He says there is nothing in the December 2014 submission "to explain in any way why the format has changed".

The questioning has kicked off and Mr Aiken is asking Dr Crawford about a submission on the domestic RHI scheme sent to then Minister Arlene Foster in December 2014 a few days before she was to present it to the Assembly.

Included in this submission is a draft press release and draft speech for the minister.

Mr Aiken reads out a section in the submission on possible questions that could be put to the minister by MLAs on the length of time it has taken, the tariffs, caps on the domestic RHI scheme and a list of matters to consider for the non-domestic scheme.

Image source, Getty Images

What is not in this list of matters is what Mr Aiken is most interested in. He points out that cost controls do not feature.

Dr Crawford says he cannot recall if it was raised in the Assembly debate either.

Image source, RHI Inquiry

Dr Crawford prepares himself for his second day of questioning this week.

Yesterday he denied providing "insider information" to poultry giant Moy Park over RHI.

Once again, inquiry junior counsel Joseph Aiken is the man at the lectern with the facts at his fingertips.

A son of a farmer from Beragh in County Tyrone, Dr Andrew Crawford is a former employee of the Ulster Farmers' Union.

He was an assistant to the former DUP MEP Jim Allister before the North Antrim politician quit to form the Traditional Unionist Voice.

Dr Crawford was an adviser to Arlene Foster when she was enterprise minister during the time the RHI scheme was created, and followed her to the Department of Finance and Personnel.

Former DUP minister Jonathan Bell accused him of preventing the closure of the scheme, but Dr Crawford denied that.

He was also named by senior civil servant Andrew McCormick, in a hearing of the Northern Ireland Assembly's Public Accounts Committee, as the adviser who exerted influence to keep the scheme open - although Dr McCormick said he had no evidence for his claim.

Dr Crawford resigned as a DUP ministerial adviser shortly after that but denied Dr McCormick's claim and said he had "acted with complete integrity".

An independent inquiry into the RHI scandal was established in January last year by the then finance minister Máirtín Ó Muilleoir.

He ordered it in the wake of the huge public concern and what was then a developing political crisis surrounding the scheme.

The RHI Inquiry began in November and Sir Patrick Coghlin (below), a retired Court of Appeal judge, is its chair and has been given full control over how it will operate.

Image source, Pacemaker

It will look at:

• the design and introduction of the RHI scheme
• the scheme's initial operation, administration, promotion and supervision
• the introduction of revised subsidies and a usage cap for new scheme claimants in 2015
• the scheme's closure

For more information on the RHI Inquiry, you can read our handy Q&A.

When the scale of the overspend emerged, public and political concern rocketed.

As the minister in charge of the Stormont department that set up the RHI scheme, the Democratic Unionist Party (DUP) leader Arlene Foster faced calls to resign from her role as Northern Ireland's first minister in December 2016.

She resisted, and Sinn Féin's Martin McGuinness then quit as deputy first minister in protest at the DUP's handling of what had by then become a full-blown political crisis.

That move brought about the collapse of the Northern Ireland Executive. Now, more than a year on from that,Northern Ireland remains without a devolved administration.

You can find much more detail on the RHI scheme in our need-to-know guide.

The budget of the RHI scheme ran out of control because of critical flaws in the way it was set up.

Claimants could effectively earn more money the more fuel they burned because the subsidies on offer for renewable fuels were far greater than the cost of the fuels themselves.

The most recent estimate for the overspend was set at £700m, if permanent cost controls aren't introduced.

The massive overspend bill will have to be picked up by the Northern Ireland taxpayer.

The Renewable Heat Incentive scheme - or RHI for short - came to the fore of the Northern Ireland public's knowledge in late-2016... and the fallout from the scandal attached to it is still being felt in the region's politics today.

The scheme was set up by the Northern Ireland Executive in 2012, as a way of encouraging businesses to switch from using fossil fuels to renewable sources for generating their heat.

Those who signed up were offered financial incentives to buy new heating systems and the fuel to run them.

Welcome back to Stormont's Parliament Buildings for Thursday's evidence session of the RHI Inquiry.

It's a bit on the damp and dreary side out of doors so why not stay with us as former DUP special adviser Dr Andrew Crawford returns for his second consecutive day of questioning.

The session kicks off at 09:45.

Stay with us for the live video feed and commentary.