Panel member Dame Una O'Brien raises a point made by poultry farmer Tom Forgrave when he gave evidence last week.

Concerns were raised about the working conditions of the catchers whose job was to remove poultry from the sheds - it appeared that the boilers were still set to high temperatures when they should've been switched off.

Mr Mark says Moy Park was aware of the potential "weakness" in the scheme "that it gave that incentive to overuse" heat.

The witness says the company warned farmers that they needed to be responsible in their use of heat.

It also reminded them that the scheme could be policed and that generating heat for the primary purpose of getting payments was illegal, he adds.

An idea of the "perfect chicken house" was laid out in a Moy Park presentation given to poultry farmers in February 2013.

In an image on one of the slides, a bag labelled "swag" sits outside a poultry shed next to a plump chicken.

Image source, Getty Images

The inquiry barrister Mr Lunny suggests it could mean the rewards on offer from the RHI scheme were very high.

"You could certainly say that," replies Mr Mark, "or you could also assume it's saying that there's a lot of money being pumped into big landowners who are getting the benefit of some of these schemes."

Image source, PA

Mr Mark wrote in an internal Moy Park email in July 2014: "More money in burning [wood] pellets than raising chicken!"

It became clear that the returns from the RHI scheme were much greater than Moy Park had set out in its promotional material - the £10,000 a year estimate the firm had made in 2013 was a very conservative one.

The witness says that factors such as the increase in the amount of heat farmers needed to use in their poultry houses and a drop in the price of biomass fuel "improved the performance" of the scheme for claimants.

Moy Park could see that the RHI scheme wasn't going to last because the firm believed the rewards it offered would be dropped as more people signed up, says Mr Park.

Newsletters issued by the firm to its farmers urged them to get on board early.

One read: "The RHI scheme is still open for new applicants but there's no guarantee this will remain open indefinitely so those who go early will ensure they get the 20-year contract!"

In November 2013 Moy Park began giving presentations encouraging the switch to biomass heating - those invited included farmers, banks and Invest NI, Northern Ireland's economic development agency.

Invest NI - a non-departmental public body - was even sent an email explaining the short payback times available through the scheme.

In a presentation that Mr Mark gave in Ballymena in County Antrim and Dungannon in County Tyrone in October 2014, he said the scheme offered "great payback".

Moy Park's first analysis of the RHI scheme in 2013 gave an indication that the cost of installing a biomass boiler could be recouped within three years.

Mr Mark tells the inquiry that a boiler may have typically cost about £30,000 and a conservative use of it gave the potential to earn £10,000 a year from the scheme.

The firm was "actively encouraging" its farmers to consider signing up to the scheme, he says.

"We saw it as a bona fide scheme; we saw it suited the poultry industry; we felt it was something we should advise them to look at."

As early as March 2014 Mr Mark observed in an internal Moy Park email that poultry farmers were "flocking" to biomass-powered heating systems.

He said that the move to biomass "enhances returns" and as such "we encourage this as it is a sound thing to do".

Asked about communication with Stormont departments at this time, Mr Mark says he wasn't in contact with the Department of Enterprise, Tade and Investment (DETI), which was running the scheme, but officials later contacted him.

He says he had very little contact with the agriculture department, mainly in terms of training the farmers, although he's sure other parts of Moy Park were in touch with it.

Out of the 1,526 poultry houses in Northern Ireland that supply Moy Park 943 - about 62% - are on the RHI scheme, according to figures from August last year.

Mr Lunny says it's fair to say that Moy Park's expansion has led to "caused or contributed to " a large number of farmers installing heating systems that were eligible for the scheme.

Image source, Getty Images

It determined in 2013 that all new poultry sheds built by its suppliers would have to be heated by hot water systems and the it funding its farmers to make the switch.

It repaid the vast majority of the of the cost of building new sheds, minus the cost of boilers to heat them, over a 10-year period.

Moy Park received significant interest from farmers who approaching the firm with an interest in becoming poultry growers, says Mr MArk.

But often their sites were unsuitable - maybe there were houses close by or the land wasn't level - and typically out of seven or eight expressions of interest only one would be suitable.

Sir Patrick suggests that the interest from farmers who weren't quite unsuitable "suggests to me that their drive was not so much the production of chickens as opposed to the income from the RHI".

The witness says he didn't see it that way and that when Moy Park looks to expand "we always look to our existing growers".

Moy Park had an eight-year plan from 2010 to grow the UK poultry business from producing four million birds a week to six million.

Northern Ireland produced about 45% of those birds with 55% coming from farms in Great Britain.

Image source, Getty Images

Part of that expansion plan involved updating the heating technology used in poultry sheds to a hot water systems - effectively central heating - rather than old-fashioned direct gas heaters.

The new systems were generally powered by biomass boilers.

The firm's growth plan involved the building of 400 new poultry houses in Northern Ireland - by December 2015 a total of 230 had been constructed, with 100 more being built or in planning and another 100 in the pipeline.

David Mark takes the oath and settles into the witness chair to face questions from inquiry junior counsel Donal Lunny.

Bit of background - after a lengthy career in the agri-food sector Mr Mark joined Moy Park in 2013 to help the firm's growth in expanding its poultry growing facilities in Northern Ireland.

Mr Mark'switness statement is available for you to read on the inquiry's website, external.

Image source, RHI Inquiry

The six board areas that Mr Mark will face questions on. They are:

• the recent expansion of Moy Park's poultry growing facilities
• Moy Park's promotion of the RHI scheme and awareness of the high rewards on offer
• Moy Park's pricing system for its contract farmers
• interaction with the Stormont department running the scheme
• his interactions with DUP adviser Dr Andrew Crawford
• abuse of the scheme in the poultry sector

At the start of business inquiry chair Sir Patrick Coghlin has a few words about the end of term, filling us in on what's going to be happening over the next two months.

There will be no witness sessions until Tuesday 4 September but the inquiry will take stock of the written and oral evidence and continue its investigations and new witnesses will be invited to give statements.

Image source, RHI Inquiry

"So while you're all away enjoying yourselves the inquiry will continue its work," he says.

"How can you enjoy yourselves without the inquiry?" panel member Dr Keith MacLean chips in.

BBC News NI

Image source, PA

The inquiry has been told that there was an attempt to "protect" Arlene Foster during the closure of the RHI scheme, it emerged.

It was revealed by senior civil servant Chris Stewart that a former DUP adviser has made a reference in his witness statement to protecting the former first minister from blame.

Mr Stewart also said there was a "desire" in the DUP to make it appear that former enterprise minister Jonathan Bell had sole responsibility for what was an unpopular decision to shut down the scheme in 2016.

BBC News NI

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.

Image source, PA

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, a year-and-a-half 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.

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.

Ahhh, summertime! It's the last day of the Renewable Heat Incentive before everyone can head off on their holidays.

Yes, the inquiry is due to finish its public hearings for a little while to give those involved a summer break.

But there's still the significant matter of today's inquiry question time with the poultry production giant Moy Park to get through.

Its former chief executive and another senior representative from the firm will be facing the inquiry panel shortly - you can watch it at the top of this page and we'll bring you all of the key details throughout the day in our live text commentary.