The lunch at the upmarket Sydney eatery Rockpool in early December 2010 was as expensive as it was exclusive. Little did the seven diners know that the link that had drawn them to lunch that day would fracture friendships and destroy careers.

A $30,000 donation to the Liberal Party by a little-known water infrastructure company with only 10 staff and one contract had secured the presence at Rockpool of Opposition Leader Barry O'Farrell, the odds-on favourite to win the next NSW election that was only months away.

Also at the private lunch on December 3 were Liberal Party state treasurer Arthur Sinodinos, the Liberal's chief fund-raiser Paul Nicolaou, controversial businessman Nick Di Girolamo, his friend rugby league legend Benny Elias, restaurateur Sal Navarra and businessman Tony Karam.

Except for Mr O'Farrell and Mr Elias, the lunchers had a common interest in Australian Water Holdings. They were desperately hoping that once in power, the O'Farrell government would approve a public private partnership (PPP) with AWH that would make many of those at the lunch seriously rich.

Four years down the track, the Independent Commission Against Corruption has cut a swath through most of the Rockpool lunchers.

Mr Nicolaou quit his roles with both the Liberal Party and as NSW chief executive of the Australian Hotels Association.

Senator Sinodinos stood down as assistant treasurer.

Mr Di Girolamo's reputation is in tatters over allegations of AWH's overcharging and alleged fraudulent billings to Sydney Water, including for political donations.

Also scrutinised were his connections to the family of corrupt powerbroker Eddie Obeid. The corruption watchdog heard that Mr Obeid misused his political position in an attempt to gain contracts for AWH that would have reaped up to $60 million for his family.

Mr O'Farrell sensationally resigned as premier in April this year after denying at the ICAC he had received a bottle of expensive wine from Mr Di Girolamo. In April 2011, four months after the Rockpool lunch, Mr Di Girolamo couriered a $3000 bottle of Grange to Mr O'Farrell, who replied with a thank you note.

The month before the lunch, Mr Sinodinos was made chairman of AWH and the company's board minutes note AWH "expected that our PPP would form part of the 100 Day Plan of the Barry O'Farrell Government".

The ICAC later heard that despite standing to make up to $20 million if the PPP went ahead, Senator Sinodinos never mentioned to Mr O'Farrell or other ministers he lobbied that he had "skin in the game".

At the time of the lunch Mr Nicolaou failed to mention to Senator Sinodinos that his private lobbying company had received almost $200,000 in fees from AWH, the inquiry into AWH heard.

The senator was similarly unaware that AWH had donated $74,000 to the Liberal Party while he was on the board of AWH and at the same time party treasurer.

Mr Navarra, Mr Karam and other AWH shareholders are now suing Mr Di Girolamo and Senator Sinodinos and other AWH directors in the Federal Court for misleading and deceptive conduct, a claim the former AWH directors reject.

Senator Sinodinos declined to answer Fairfax Media's questions as to who had invited him to the lunch, who did he understand was paying and what was discussed.

Mr Nicolaou and Mr O'Farrell did not return calls.

The Liberal Party has forked out an estimated half a million dollars in legal fees for Mr Nicolaou and other party officials who appeared at the two overlapping ICAC inquiries that have torn apart the party this year.

"Costs have been met from existing resources. State campaign funds have not been used," party state director Tony Nutt said.

These costs do not include Senator Sinodinos' substantial legal fees. It is understood that some, but not all, of the senator's legal expenses will be covered by AWH's Directors and Officers insurance policy.

Mr Sinodinos declined to answer whether any third party has provided assistance with his legal expenses but he claimed the basis of Fairfax Media's questions were "manifestly inaccurate".

ICAC: Arthur Sinodinos and the lunch that destroyed careers