We turn now to the written evidence of Peter Robinson (seen below), the former DUP leader who was first minister at the time.

He says that he wasn't aware of any communication between Timothy Johnston and anyone else regarding the RHI scheme.

He also says there was no DUP party line on RHI.

"Mr Robinson's evidence doesn't take the inquiry much further as to what communications there were during the summer of 2015," says Mr Scoffield.

Image source, PA

However, the inquiry counsel says that if Mr Robinson's evidence is correct then if Timothy Johnston played the role described by Mr Cairns then "it might be thought that he was on a frolic of his own, as lawyers sometimes say".

Inquiry chair Sir Patrick Coghlin observes that either Mr Robinson knew what was going on "or if he didn't know, the SPADs were running the show".

Mr Scoffield notes that Mr Johnston says he was not involved at all.

Mr Johnston's evidence is now being outlined.

While Mr Johnston says in his written statement that there was regular contact between himself and Mr Cairns as a SPAD colleague, he was unaware of any understood or accepted hierarchy of advisers. It it only the first minister who had the authority to give orders, he says.

Mr Johnston says that he had no involvement in the decision making process on implementing the cost controls for the RHI scheme in 2015.

Image source, RHI Inquiry

But Mr Scoffield lists a series of correspondences where Mr Johnston was in receipt of information on the RHI scheme.

Included in the correspondence on the RHI scheme Mr Crawford had forwarded the July 2015 submission and an email exchange between businessman Brian Hood (pictured above), energy consultant Austen Lennon and Howard Hastings, managing director of Hasting Hotels on the possible introduction of cost controls.

The email thread was forwarded from Mr Hastings to Mr Crawford, saying: "Not on your watch, surely?"

This email was then forwarded onto Mr Johnston.

Image source, Getty Images

Mr Scoffield outlines a conflict between Dr Crawford's second statement to the inquiry on his dealings with Mr Johnston.

The SPAD says he had a conversation with Mr Johnston about the difficulties between Mr Cairns and Mr Bell and that he had forwarded the July submission to him.

But, it is Dr Crawford's position that at no point did the two SPADs discuss a "party line" and that no party position had ever been formed.

He also says he cannot recall a meeting between Arlene Foster and Mr Cairns, but that he may have attended it.

Mr Scoffield observes that there are many conflicts of view that the inquiry will need to wade through.

"It might be that the truth lies somewhere in between. It might be that there are genuine differences of view about the character and the exchanges," says Mr Scoffield.

Mr Scoffield now turns to the written evidence of DUP SPAD Andrew Crawford.

We've already heard from Dr Crawford several times regarding his time as a DETI SPAD - by the summer of 2015 he had moved on to the Department of Finance (DFP).

In his evidence, Dr Cawford says Mr Cairns sought his advice on developments with the RHI due to his previous DETI experience.

Image source, RHI Inquiry

There was a meeting at the end of June, or beginning of July involving Mr Cairns, Dr Crawford and another DUP SPAD Stephen Brimstone.

There was further contact between Mr Cairns and Dr Crawford in August about RHI.

According to Dr Crawford, Mr Cairns was hoping to push the date for changes to the scheme back to minimise their impact.

Dr Crawford says he advised his fellow SPAD against going against the advice of officials.

This is important because the decision to delay the introduction of cost controls to the scheme contributed to the "spike" in applications in the autumn of 2015.

Dr Crawford says in his written evidence that at no point did he seek to delay the introduction of cost controls, that he didn't push to have the dated pushed back.

He says he never indicated to Mr Cairns that the introduction of controls should be put back as late as possible.

Mr Cairns' evidence states that DUP special advisers Dr Andrew Crawford and Timothy Johnson had urged him to push out the closing date for the RHI scheme as far as possible, says Mr Scoffield.

He also says Mr Cairns alleges in his evidence that Mr Bell accepted this advice "without question, comment or protest" and even "enthusiastically".

This, he says, was in the context of issues closing another energy scheme called the Northern Ireland Renewables Obligation (NIRO), which required all suppliers to source a specified share of the electricity supplied to consumers from renewable sources.

Image source, Getty Images

Mr Cairns also says that despite Mr Bell claiming otherwise, the minister was fully aware of the meetings taking place between the special advisers.

"Mr Cairns says the minister was content for a party position to be sought and implemented," says Mr Scoffield.

But Sir Patrick makes the point that this view is difficult to reconcile considering two rows between Mr Cairns and Mr Bell - one at an Indian restaurant and another at a pre-meeting breakfast - were allegedly about Mr Bell "not wanting to be pushed around".

Mr Scoffield says that in fairness to those mentioned in Mr Bell's evidence he's going to outline their viewpoint of the events of summer 2015.

He turns first to the written evidence of Mr Bell's special adviser (SPAD) Timothy Cairns.

According to Mr Cairns he would from time time to time receive instructions from the office of the first minister, Peter Robinson. and this was often relayed by the first minsters advisers.

The first minister's SPADS were seen as having a higher level of seniority.

One adviser, Timothy Johnston (Below on left with Peter Robinson), is said to have the highest level of seniority.

Mr Cairns took some sick leave in the period following his falling-out with DETI minister Jonathan Bell in London on 9/10 June 2015.

Mr Soffield says there was a "clear the air" meeting on Mr Cairns' return to work a few weeks later.

In his evidence, Mr Cairns says that, at a meeting in June, Timothy Johnston "stated that tariff controls would not be introduced" and that he should work with another DUP SPAD, Andrew Crawford, at looking into an alternative.

Image source, Getty Images

Mr Scoffield gives a short recap on Friday's proceedings.

To bring us up to date, we heard:

• Key communications from a July 2015 submission to the former enterprise minister Jonathan Bell on the RHI scheme.
• Mr Bell's written evidence to the inquiry.
• Writen evidence from Dr Andrew McCormick, who was then permanent secretary for the Department of Enterprise, Trade and Investment (DETI).

Mr Scoffield is now summarising more written evidence.

Image source, RHI Inquiry

Inquiry senior counsel David Scoffield QC gets the session underway.

He'll be continuing with the opening of phases three and four of the inquiry.

These include the later stages of the RHI scheme up until its closure, and the subsequent political fallout.

If you were with us on Friday you'll know this allows a tantalising glimpse of where the inquiry may be headed.

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.

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.

Image source, Getty Images

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.

Image source, AFP

Yet another pleasant day on the hill at Stormont - pity we don't have a dog to take for a walk really.

Failing that, it's Day 71 of the RHI inquiry and we're hoping for another day of fascinating revelations from senior counsel David Scoffield QC.

Stick with us for live updates throughout the day.

The action starts at 09:45.