The mother of John Banks' alleged love child has called on the former Cabinet Minister and Auckland mayor to "just own up to his responsibilities".
This week, Antony Shaw, 47, asked a judge to declare that the former politician known as "Banksy" was his biological father.
The court action arose after years of uncertainty around the identity of his father.
On Thursday, Justice Tim Brewer said a simple DNA test could resolve the dispute - and prevent a costly High Court trial. Neither Banks nor Shaw - who lives in Japan - attended the court hearing.
If the case is successful, Banks, 70, could be declared Shaw's next of kin with legal implications relating to potential claims against Banks' will.
In an exclusive interview with the Herald on Sunday, Shaw's mother, Pam Mayes, said of Banks: "John is very silly. I think every child has the right to know who their parents are".
Mayes claims she had a relationship with Banks when she was a Waikato Hospital nurse in the late 1960s.
At the time Banks was a salesman for a pharmaceutical company.
The pair first met at a party, she said.
Mayes told the Herald on Sunday the relationship initially ended when she found out she was pregnant.
"I was going to have him [Antony] adopted but there was no home available," she said.
"So I kept him".
Banks and Mayes continued seeing each other "on and off" for two years after Antony was born, she added.
"He was my first love," she said.
For many years Shaw grew up believing a Chinese man named Harry, a former boyfriend of his mother's, was his father. He was brought up by Mayes and her husband, Tony.
But Mayes said she finally told Shaw about his biological dad after Banks revealed publicly the impact of not having a relationship with his own father in his Parliamentary valedictory speech in October, 1999.
The next year Antony - who had by then made Japan his home - travelled back to New Zealand to meet the man he was told was his biological dad.
But the meeting never happened, Mayes said, something which had severely impacted on her own relationship with her son.
"That's why I think Antony was annoyed with me all these years."
Mayes, 69, only found out about her son's paternity case after reading about it in the New Zealand Herald last week.
"I thought, 'Oh, here we go - another kid has come forward'. I didn't realise it was Antony till I read it".
Shaw lives in Japan with his wife and their 19-year-old son.
Mayes said she had been surprised neither her son, nor his legal team, had contacted her about the paternity case.
"I said to my husband, 'It seems unusual the lawyers wouldn't want my help'. I could be the person to support him through this the most but I guess he has enough information to do it."
Mayes, who is retired and caring for her husband who has prostate cancer, said she had tried to "park" her son's alienation from her.
But the pain was never far away, she added.
"I now regret I ever told Antony about John but back then I thought I was doing the right thing," she said.
"He is my son. I love him and I will always be there for him. It's a shame it's come to this and I fear the opportunity to make peace has sailed away."
Banks did not respond to an approach from the Herald on Sunday to comment.
Shaw's lawyer, Jacque Lethbridge said her client also didn't want to comment.
"These proceedings were filed at the end of last year, and despite being served in April with a full set of proceedings including the affidavit evidence, but he just hasn't engaged at all."
The next hearing in the dispute is set down for June 29.
Meanwhile, Banks has sold his multi-million dollar Auckland luxury penthouse apartment himself, saying he was a "pretty gun salesman" and achieved just under his asking price.
Last June, Sothebys International Realty was marketing the 382sq m Stamford Residences unit for $5.25 million.
Banks said he got "just under $5 million" for the property, which was advertised with silk-lined walls and marble-clad bathrooms .
"I sold it myself because I am a pretty gun salesman and if you want to sell something at that end of the market, you have got to do things outside the square to promote and market it," he said.