Mr Scoffield takes the witness through a number of emails from Aecom, the consultancy that drew up a report on a possible RHI scheme, to DETI in 2010 regarding their final paper.

In one of these, Andrew Turton of Aecom suggests that a meeting should be used to ensure that their recommendations should "fully reflect DETI's views".

Image source, RHI Inquiry

He puts it to Ms Clydesdale that to "a member of the public reading these emails it might be surprising the level of direction which it appears that the consultants are being given by the department".

Ms Clydesdale says much of this interaction is to do with "correcting the report, correcting inaccuracies in the report - cross-referencing the report in terms of tables and recommendations not matching".

Ms Clydesdale settles back into her seat for her questioning by the senior counsel, which it's important to remember is inquisitorial in nature, not adverserial.

Her full written witness statement is available to read here, external on the inquiry's website.

Image source, RHI Inquiry

Ms Clydesdale outlines the details of the Aecom Pöyry report in 2010, which was a research paper commissioned by DETI into the potential for the development of renewable heat production in Northern Ireland.

It looked at whether a target of producing 10% of Northern Ireland's heat through renewable sources was possible - it determined that it would be, but to do so would need "significant government intervention", says Ms Clydesdale.

The inquiry's senior counsel David Scoffield QC introduces the day's business, and says that there will have to be an extra session on 18 December to catch up on missed business from a couple of weeks ago.

Image source, RHI Inquiry

The inquiry's first witness Alison Clydesdale is then sworn in.

Mr Scoffield explains that Ms Clydesdale worked at a senior level in the Energy Division at the Department of Enterprise, Trade and Investment (DETI) during the early years of the RHI scheme.

Conor Macauley
BBC News NI Agriculture and Environment Correspondent

BBC News Northern Ireland

An independent inquiry into the RHI scandal was established in January 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.

Image source, Pacemaker

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

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 last year.

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, and as we near a year on from that Northern Ireland remains without a devolved administration.

If you want a bit more detail on the background to the scandal and the subsequent inquiry, here's our need-to-know guide on the RHI scheme.

There were critical flaws in the way the RHI scheme was set up that left it open to abuse and that later saw its budget spiral out of control.

Crucial cost curbs that existed in a similar scheme in Great Britain were not replicated and claimants could effectively earn more money the more fuel they burned.

Image source, Getty Images

That was because the subsidies on offer for renewable fuels were far greater than the cost of the fuels themselves - the scheme was later nicknamed "cash-for-ash" for that very reason.

As a result, the scheme racked up a huge projected overspend - £700m at the most recent estimate, if permanent cost controls are not introduced - and the bill will have to be picked up by the Northern Ireland taxpayer.

Need a quick refresher on the Renewable Heat Incentive (RHI) scheme? Well, we're here to help...

It came to the fore of the Northern Ireland public's knowledge in autumn last year - few people, if anyone, would have expected it to have the consequences it has done in the months that followed.

It 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.

It's a bright-but-chilly day up here at Stormont's Parliament Buildings.

Still no sign of a deal to restore power-sharing and get the Northern Ireland Assembly up and running again, but we're here for more of the RHI Inquiry.

Image source, AFP

It paused from the public evidence sessions last week after an opening fortnight of introductory statements.

Today we'll hear from the first witness - Department for the Economy (DfE) civil servant Alison Clydesdale - and we'll bring you live video and text commentary throughout the day.