William Luong appeared as a witness on Thursday at the Independent Commission Against Corruption and claimed he would have paid Mr Maguire at least $690,000 as an 'introductory fee' from his $6.9 million commission if the Waterhouse family could have sold their land for $330 million.

ICAC also heard claims that Mr Maguire tried to improve road access and planning zones for the land in an attempt to save the deal.

Mr Luong also claimed Mr Maguire told him to delete messages on the WeChat smartphone app.

Mr Luong said the deal "stalled" in late 2017 as the Chinese investment company Country Garden "calculated" high risk in buying 230 hectares near the future Sydney West Airport.

In an intercepted phone call, Mr Maguire told Mr Luong the "risk averse" Country Garden had "never got their testicles out, put them on a razor blade and worried about an earthquake".

Mr Luong agreed with counsel assisting ICAC Scott Robertson that he "could" have paid Mr Maguire more than $1 million if the former Wagga MP's "friend" Louise Raedler-Waterhouse requested it. "We would normally pay introductory fees of 10 per cent," he said.

ICAC heard multiple calls between Mr Maguire and Mr Luong concerning what they thought would be a successful deal.

"We desperately need this one to happen," Mr Maguire said in one call.

"It's a good Christmas gift," Mr Luong replied.

Mr Luong boasted about how he had secured for Ms Raedler-Waterhouse, daughter of prominent bookmaker Bill Waterhouse, a "top price" at 30 per cent above market.

"Wow," Mr Maguire replied and said the $330 million price was "pretty good going".

"Good, well done. You have done well," he said.

When Mr Maguire expected a letter of offer for the sale was on its way, he invited Mr Luong to a dinner at Parliament House where Mr Luong said he had "close contact" with NSW Premier Gladys Berejiklian.

However, Mr Maguire's tone shifted in later calls when the deal fell into doubt.

ICAC heard an intercepted call in which Mr Maguire said he had "got an appointment with Louise with the Sydney Planning Commission to talk about development and getting access to the road" so he could get a "quicker sale" for the land.

Mr Maguire called Roads and Maritime Services "a pack of bastards" for not cooperating to "move the road".