David Grier was in New York City on Wednesday night when a BBC documentary on Rangers was aired in Scotland.

It wasn't long before his phone started ringing, because Grier and his insolvency firm, Duff & Phelps, had just been roundly trashed.

Daly's documentary cast doubt on the integrity of the Rangers administrators, and in particular on Grier himself, a senior partner of Duff & Phelps. The BBC's central allegation, citing documentation, was that Grier knew all along about Craig Whyte's dodgy plan to use funding provided by investment firm Ticketus to finance his Rangers takeover.

It is an allegation Grier has denied, and never more vehemently than yesterday when he ventured to explain to the Sunday Herald why the BBC claims are untrue.

"I can tell you categorically – at the start of all this neither I nor Duff & Phelps had any knowledge of the way Craig Whyte intended to use Ticketus funding to take over Rangers," said Grier. "Craig Whyte created an illusion – which was that he had his own money. That is what all of us believed."

Those who watched Wednesday night's airing of Rangers: The Men Who Sold The Jerseys may have real trouble believing in Grier's innocence. The BBC's Mark Daly uncovered emails which appeared to show Grier having very early knowledge of Whyte's involvement with Ticketus – a deal which has subsequently been seen to be ruinous for Rangers.

Yesterday, however, Grier robustly defended himself. He also claimed the old Rangers board under chairman Alastair Johnston positively egged Whyte on to get involved with Ticketus.

"What we do at Duff & Phelps is, we provide advice and assistance to people in the corporate world," Grier said. "Craig Whyte first came to our attention round about December 2010 when we read in the press that he was interested in buying Rangers. So I phoned Craig Whyte speculatively. I basically said to him: 'I don't know you, but I see you want to buy Rangers - can we help you?'

"He replied, 'yes, possibly you can', and he asked us if we knew Lloyds Bank at all, which we did. We had a relationship with Lloyds due to various jobs we'd done. So we met Craig Whyte."

Grier then says Whyte was very keen to buy Rangers – but that there were various sticking points. "Whyte made it clear to me that he didn't want to pay the full value of the debt at Rangers to Lloyds, which was then around £24 million," said Grier. "He said to us: 'Anything under £20m and I'll do it.' So we acted for him in terms of speaking to Lloyds and - we got agreement on a debt reduction from £24m to £18m, on condition of the lease for the Albion car park being continued [by Rangers].

"It was at this point that we conducted discussions with Whyte and the old Rangers board. And there were tensions.

"At that time the outcome of the big tax case was still awaited. Basically, Rangers were saying that, if the big tax case went against them, there is no way the club could survive.

"So our plan [Duff & Phelps on behalf of Whyte] was to go to HMRC and reach a time-to-pay arrangement. So if the bill was, say, £30m, then we'd hope Rangers could pay it back over a set number of years."

Grier claims that at the crucial meeting of April 24 last year – when Grier, Whyte and the Rangers board met – a new, key factor was introduced.

"Craig Whyte already knew that Rangers used Ticketus for revenue streams – it was an established procedure at the club. Indeed, the old board actually encouraged Whyte to go down the Ticketus route.

"At the meeting of April 24 [2011] - the Rangers board were asking Whyte about his means and his wealth. One of them said to him, 'have you thought about going with Ticketus?'

"I can stress to you: we had provided Craig Whyte with advice on Lloyds, on HMRC, and on the rights of the lender in any purchase of future season-tickets - we just saw Ticketus as part of Whyte's back-up financial support.

"Everyone back then believed that Whyte had the money. We'd had confirmation from Whyte's lawyers [Collyer-Bristow] about his own funding. In our eyes no vast upfront Ticketus money would be required."

So, then what happened? By Grier's version of events, he and his Duff & Phelps staff only became aware of the true extent of the Ticketus scenario in late July 2011 – which contradicts the BBC's allegation that Grier knew what was happening all along.

The so-called "raising of invoices" for Ticketus money in June – which the BBC says nails Grier – is also disputed.

"It was late July, early August when things started to not look right to us," says Grier. "The club had received a tranche of money from Ticketus, of around £9m, in June. Remember, money from Ticketus was quite natural at Rangers. If someone had said, 'here's an invoice for £25m' then that would have been very different. But Ticketus were well established as a funder of Rangers. Then, in about late July, Phil Betts [then a Rangers director] panicked and said: 'We are due Ticketus £7m.'."

Crucially, Grier maintains that Duff & Phelps only at this point became alarmed at Whyte's antics in regard to Ticketus.

"We'd had no knowledge of what Craig Whyte had done," says Grier.

Grier claimed the illusion was created by Craig Whyte that he had the money for the purchase when he clearly didn't.

"We have legally gone after Ticketus, because we believe their Rangers arrangement does not hold up under Scots law. - They are not coming after us, because they know we were not in on the deal.

"Similarly, we are legally pursuing Collyer-Bristow for £25m. Why are Collyer-Bristow not saying to us, 'but you knew about this'? - it is because they know that we didn't know about the deal."