Mr Aiken is rather pleased to be finished ahead of time on what has been frankly one of the dullest days of proceedings so far, and the inquiry team may get to leave the building before dark for a change.

Sadly, little or nothing has penetrated our cubbyhole about the great affairs of state happening elsewhere at Stormont.

Image source, Press Eye

We'll be back with more live coverage of the RHI Inquiry at 09:45 tomorrow for an all-day session with DETI economist Sam Connolly - he's been much discussed in previous sessions but this is first appearance in person, so join us then.

Have a very good evening!

Mr Aiken turns to events in February 2012, eight months before the launch of the RHI scheme.

His characterisation of a discussion between Ms McBurney and Treasury official Keith Jarrett illustrates the tortuous nature of today's proceedings.

Image source, RHI Inquiry

"The two of you had both had prior knowledge about something in fact, but you don't remember it and are having a discussion where he's telling you how things would normally be, and what you understand from that, as I take it, is you would be giving a short few lines saying what Peter Jakobsen didn't say in 2010, which is: 'We are going to go ahead with the scheme.'"

Yeah, it's been one of those days...

Finance officials did not do enough to make sure that the Northern Ireland budget would be hit if the RHI scheme went over its budget, says Ms McBurney.

She tells the inquiry that she assumes that DFP "would've sought assurances" from DETI that it could live within the £25m scheme for the scheme.

"Obviously we didn't take enough action to make sure that was the case," she adds.

There was "something fundamentally dangerous" about the communication structures between the Treasury and the Stormont departments working on the RHI scheme, according to inquiry panellist Dr Keith MacLean.

He suggests that DFP should have made more effort to find out how the £25m that was provided for an energy scheme in Northern Ireland would be used.

Image source, Getty Images

Sir Patrick says the finance department should have sought more detail from DETI about the scheme it was intending to create, and he says he finds it "difficult to understand why DFP lay back and said: 'Here's your pot'".

Ms McBurney accepts that having so many different civil service teams from a number of departments communicating with each other "weren't helpful".

Before the lunch break, questioning turns to the concept of AME funding and how it applies in Northern Ireland.

"If Westminster was to decide that we're going to fund a new benefit that would be an AME, and you'll simply introduce the same benefit and you'll suck down the AME to pay for it," Mr Aiken says.

Image source, Getty Images

Sir Patrick observes: "In many ways the notion of a capped budget for AME is a contradiction in terms if you look at what the GB spending statements are each year".

"I certainly couldn't argue with that," Ms McBurney says.

Mr Aiken asks whether it would've been "wise" for Stormont finance officials to ask the Treasury why that mechanism was being used.

Ms McBurney says that in hindsight the Department of Finance and personnel (DFP) should've sought clarification in writing about how the funding would work.

Image source, RHI Inquiry

She says the funding had "come out of the blue" and DFP would've informed DETI that it was being made available.

Sir Patrick asks why, given that the RHI scheme had the potential to be "volatile", alarm bells were not ringing with finance officials to ask more questions about it. He wonders if it was just a case of them thinking: "'They're giving us money - let's take it.'"

Ms McBurney says she had no awareness of similar scheme and the associated risks, and assumed that DETI would've looked into them when it was investigating how it could use the available money.

The funding mechanism for the RHI scheme was unusual type, and one that many of the civil servants who have appeared before the inquiry have said they had never encountered before.

Mr Aiken notes that "caps that were being applied" and says that was "quirky" in terms of this particular type of funding.

Image source, RHI Inquiry

Ms McBurney accepts that it was not the norm.

Inquiry chair Sir Patrick Coghlin asks what the result is if the spending cap is exceeding.

Ms McBurney says the result would have been that "we would have had to fund it ourselves" from DETI's own wider budget.

There is "an unfortunate lack of documentary record" of discussions between civil servants about the budgetary arrangements of the RHI scheme, says Mr Aiken.

Image source, Getty Images

Ms McBurney says it's "equally frustrating" for civil servants looking back on it that conversations were sometimes not followed up with emails that would've left a document trail.

The next witness to be sworn in is Joanne McBurney, the head of the central expenditure division (CED) at the Department of Finance, managing public expenditure.

She was an accountant within CED and her particular responsibility between 2008 to 2010 was managing in-year monitoring rounds.

Image source, RHI Inquiry

From 2010 to 2012 she was in charge of the Northern Ireland Executive's budget process, ultimately leading to the preparation of a budget act.

You can find Ms McBurney's written statement on the inquiry's website, external.

There are no more questions for Ms Brankin from the inquiry counsel, so he opens the floor to the panel.

But in the meantime, Ms Brankin has lifted her bag and headed for the exit!

Image source, RHI Inquiry

Just as she reaches the door, inquiry chair Sir Patrick Coghlin looks up to see her on her way and there's laughter in the Senate chamber.

He jokes: "I was about to compliment you on your wisdom in getting away as quickly as possible!"

DETI applied to Stormont's finance department to roll forward its 2011-12 underspend on the RHI scheme into the next financial year.

Mr Aiken puts it to Ms Brankin that "your application didn't provoke any difficulty with [the finance department] or, it seems, [the Treasury]".

Image source, RHI Inquiry

He says the 90% underspend of the £2m budget for the scheme's first year was carried forward but that was "entirely inconsistent" with what Ms Brankin had understood would be the position the previous spring.

Ms Brankin says her earlier understanding was that any such underspends would be lost.

There was "no explanation" provided for why it was allowed for the money to be carried forward, she adds.

Image source, Getty Images

Gather your friends and family round the TV or laptop - our live stream is working again!

In November 2011, DETI officials put together a submission for the then enterprise minister Arlene Foster, part of which outlined that the department was seeking to carry its initial underspend in the RHI scheme over to the next financial year.

Inquiry counsel Joseph Aiken suggests that the submission that Mrs Foster received was inaccurate, and did not clearly explain the financial arrangements regarding the RHI scheme.

Image source, Getty Images

Ms Brankin accepts that the crucial advice about the scheme from the Treasury official, Jon Parker, is "clearly not in the submission".

"It clearly should have been there," she adds. "It should've been edited to reflect that RHI [financial arrangements] were different."

She says that because the department was dealing with an underspend, the officials didn't flag up the advice to the minister.

Much of Ms Brankin's evidence at her last appearance before the inquiry centered on the financial arrangements for the RHI scheme.

There was much focus on a crucial email from senior Treasury official Jon Parker, who told DETI how the RHI scheme in Great Britain worked.

He said the Treasury was not paying for any overspend - instead the Department of Energy & Climate Change (DECC), which set up the GB scheme, would need to cover any overspend in future years.

Those rules would then be applied in Northern Ireland when its own scheme got up and running, he said, and there would effectively be a penalty imposed of about 5% in the case of an overspend.

Ms Brankin discussed the details of the email with Stuart Stevenson, who appeared before the inquiry this month, in order to seek clarification about what it meant.

He advised that the £25m of funding for the RHI scheme shouldn't be exceeded, but Ms Brankin tells the inquiry today that they didn't got into detail about how the budget could be kept under control.

Bernie Brankin is back in the inquiry hotseat - we first heard from her last month- and today she will finish giving her evidence.

Image source, RHI Inquiry

Now retired, she was a long-serving civil servant and was the head of the finance branch within the finance division of DETI when the RHI scheme was being set up.

You can find Ms Brankin's written witness statement to the inquiry on its website, external.

We're having a few problems with our live stream but we hope to have that sorted shortly.

Image source, Getty Images

One of our tech guys is away to give the thing a kick!

BBC News Northern Ireland

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.

Public and political anger erupted when the scale of the overspend emerged.

The Democratic Unionist Party (DUP) leader Arlene Foster (below) had been the minister in charge of the Stormont department that set up the RHI scheme in 2012 and she faced calls in to stand down as Northern Ireland's first minister in December 2016.

Image source, PA

She refused, 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.

By doing so, he brought about the collapse of the Northern Ireland Executive. Now, a full 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.

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

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

Need a quick refresher on what the RHI scandal is all about? Here goes...

The Renewable Heat Incentive scheme - or RHI for short - came to the fore of the Northern Ireland public's knowledge in autumn 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.