The High Court in London has been told that the nationalisation of Anglo Irish Bank and NAMA'S transfer of loans of a company controlling some of London's top hotels caused catastrophic financial damage to Irish property developer Paddy McKillen.
Belfast-born Mr McKillen gave evidence in his legal action against the Barclay brothers, owners of Telegraph Newspapers and the Ritz Hotel.
Mr McKillen claims the Barclay brothers unlawfully bought a share holding in Coroin, a company owned by Irish financier Derek Quinlan, which controlled Claridge's Hotel, the Connaught and the Berkeley Hotels in London.
Mr McKillen has claimed the move represented a takeover bid.
In the witness box today, Mr McKillen described the difficulties he faced in 2010 in getting fresh investors for Coroin after NAMA had taken over the company's loans from Irish banks.
The Barclay brothers subsequently bought €800m of the hotel group's debt held by NAMA.
Mr McKillen, who owned 36% of the company, claims he was denied a chance to take over the hotel group because of a conspiracy between the Barclay brothers and Mr Quinlan.
Mr McKillen described flying to Doha to attempt to sign a separate rescue deal with Qatari investors, but that it fell through.
Mr McKillen told the court that Caroin had had a close working relationship with Anglo Irish Bank prior to its nationalisation and that three employees of the bank had become investors in the company.
He agreed that nationalisation of Anglo Irish had been a serious blow for the company.
An email from Mr McKillen's PA Annmarie Ryan, read out in court, stated that "the big issue over the last few years is that the financial world has fallen apart. The banking world as we know it is a thing of the past."
A letter from Maybourne Hotel Group to Brendan McDonagh, the Chief Executive of NAMA, which was also read out in court, stated that "for NAMA to transfer loans from Anglo Irish would cause significant, catastrophic damage to the remaining equity in Caroin."
Under cross-examination, Mr McKillen was unable to say where he was domiciled in 2009 and 2010.
He told the court he travelled extensively in Asia and elsewhere and that his family had been based in California.
He said he was not sure where he was resident at that time.
When asked by Mr Justice David Richards where he called home, Mr McKillen repeated that he had been travelling a lot, but agreed that he spent more time in London than in Dublin.
Mr McKillen spent all day in the witness box.