It’s been a stressful morning at the New South Wales Independent Commission Against Corruption for former Labor minister Ian Michael Macdonald. When he slipped into the witness box at 3pm yesterday he looked full of confidence, but today’s relentless interrogation is taking its toll.

Yesterday counsel assisting, Geoffrey Watson SC, told the former mining minister he would take him through 40 times and events. “At the end of it I’m going to show to you that you did this deliberately, you created this [mining] tenement with it in mind, to profit your friends the Obeids,” he said.

ICAC is investigating allegations Macdonald made improper decisions about mining leases which could enrich the family of his friend and political ally Eddie Obeid by somewhere between $75-175 million. It’s been alleged Macdonald stood to receive $4 million in return.

We are now up to point number 14,  and it does feel as though the former leading light of the NSW Left faction is slowly sinking into quicksand.

Yesterday he said he had decided that Mt Penny, on the Obeid land, would be the site of a new mining tenement because he had simply found it in the atlas. Today he is denying he instructed the relevant government department to create this new tenement, against expert advice that more investigation was necessary. Two public servants have already given evidence that Macdonald instructed them to “create a Mt Penny tenement”.

The former politician is also denying he had told cabinet, the Parliament or his colleagues about the decision, claiming he hadn’t known the Mt Penny tenement was on the Obeid’s property. “The first time I heard about it was in the paper [The Sydney Morning Herald],” he said.

Heavy-set, bald, with a neck like a rhino, the 63-year-old radiates aggression and disdain in equal quantities, with the occasional flash of nerves. His constant bluster and obfuscation is testing the patience of the commissioner, David Ipp QC, who has described his evidence as “tiresome and time wasting”.

There has been quite a bit of argy-bargy at the bar table — “just answer the question!”; “will Mr Watson stop shouting!” — until Watson asked a question about a previous witness, whom he described as an “honest man of great integrity”.

“And so am I,” Macdonald snapped, bringing the hearing room to a stunned silence. “I won’t comment  on that,” Watson replied.

Macdonald is the biggest star of this inquiry. Last year ICAC investigated his receipt of services from Asian s-x worker “Tiffanie”, paid for by property developer and murder suspect Ron Medich. It’s alleged Macdonald received s-xual favours in return for introducing businessmen to the heads of government departments. No findings have been made in that matter.

In a way, both Macdonald and Obeid are reminiscent of many of the politicians in Papua New Guinea: their only reason for entering parliament is to gather money to enrich their tribes. In PNG, this behaviour is cultural. But Macdonald does not even pretend to have an ideology, changing allegiances on crucial Labor policy like electricity privatisation simply in order to gain influence. In Parliament for 22 years, he finally left following a public outcry over travel rorts and excessive entertainment expenses, which had earned him the nickname “Sir Lunchalot”.

It’s a long way from the Housing Commission flat in rural Victoria Macdonald grew up in with his four siblings after their father deserted them. His mother eked out a living as a housekeeper in Catholic presbyteries, impressing on young Ian the importance of education.

He worked hard at school and went to La Trobe University, where he studied history and threw himself into campus politics, joining the ALP. After graduation, Macdonald worked as a research officer in the Senate before moving to NSW to spend a decade working for then-attorney-general Frank Walker, organising to shore up Walker’s position with the Left faction. By 1988 he was appointed to the upper house of the NSW Parliament, giving a rather prescient maiden speech in which he expressed misgivings about plans for an independent commission to investigate corruption.

He has his detractors on both sides of the fence. A few years ago, Nationals leader Andrew Stoner described Macdonald as a “repeat offender when it comes to feathering his own nest at the expense of taxpayers and looking after his mates”.

But the best description of him comes from an unnamed member of his own party, quoted in 2009. “Macdonald,” they said, “was one of the most loathsome people in Australian public life, an orthodox right-winger masquerading under the ‘hard Left’ banner, a man who operates from the shadows.”