Mr George Redmond began accepting money from property developers in the mid-1960s, the tribunal heard.
"The genesis of my extra-mural activity went back to around 1965," Mr Redmond told counsel for the tribunal, Mr Des O'Neill SC.
He described how he became friendly with a number of people working in the construction industry in the 1960s. Mr Tom Brennan, and a man he described as "P. Treacy" who worked with the Gallagher Group, were two particular friends.
Mr Redmond told the tribunal he was an assistant principal in the development department of Dublin Corporation from 1965 to 1967.
"I had developed some expertise in relation to the council. I had a very good relationship with P. Treacy - he worked in the county council. We were very close friends [and] he went to work for the Gallagher Group.
"When the Planning Act came in I certainly took an interest in it. From time to time he would come to me and ask me about things.
"At Christmas times he would give me something, and probably at other times . . . He was doing very well and he let some of it rub off on me. That's how it started. It's as simple as that."
Around the same time he developed a relationship with Mr Tom Brennan.
"I was in the corporation, but I knew a lot about the council. If you asked for my opinion about something I would give it."
He said he never asked for money. "I never sought anything. If it was offered to me I took it. I shouldn't have."
He said he never put a monetary value on his opinion.
"I'm not a qualified planner. I'm not a qualified engineer, but I had a very good understanding of the demands of the Planning Act . . . Some people valued that."
Mr Redmond said he regretted his actions, but stressed that the circumstances of the time were very different from nowadays.
"The relationship I had in those days with both of them was somewhat innocuous really. But they were both generous and I had money as a result."
". . . I can see looking back how it all went wrong. Even [Frank] Dunlop's evidence, how situations like that came about. I can see how it happened.
"But in those days you could buy houses in Portmarnock and Malahide and Skerries and Balbriggan.
"There was no problem, there was no zoning in the county in those days. They didn't have a development plan. There was a huge amount of choice. There was nothing like the sort of pressures and the shortages that exist today."
He said that once the extra payments went into his bank account they "never came out". He had even continued saving "a considerable amount" of his salary, he said. "That was my nature."
It was only in recent years that money came out of the account, for monetary gifts to his grandchildren and other such outgoings.
Mr Redmond said he had justified his advice on planning matters to himself by thinking: "I'm corporation, that's county council."
However, he did not want to try to excuse his actions. "It's with the greatest humility and regret all this has to be faced now."
Mr Justice Flood adjourned the tribunal until this morning.
