The widower of Colleen McCullough is accused of manipulating his ill wife to secure her fortune, according to court documents filed in the NSW Supreme Court.
A will, effectively revoking an earlier bequest to the University of Oklahoma Foundation, was signed by Dr McCullough at her home 12 days before she died in a Norfolk Island hospital from a series of strokes.
But the late author's friend and executor, Selwa Anthony, the plaintiff in a legal battle to be heard over five days by the court from May 22, has challenged the will's validity claiming it was signed by Dr McCullough in ''suspicious circumstances''.
Dr McCullough was ''substantially bedridden'', unable to make or receive phone calls, had advanced macular degeneration which caused ''severe vision impairment'' and was ''not capable of reading the document'' she allegedly signed, Ms Anthony said in pleadings filed to the court.
In them, Ms Anthony accuses Mr Robinson of taking advantage of his late wife's ''poor health, isolation, fatigue and dependence of the deceased, so as to dominate, overbear and overburden her''.
In his defence, Mr Robinson, a descendant of the Bounty mutineers who settled on Norfolk Island, claims he is the rightful sole beneficiary of his wife's estate and the 2015 will was prepared properly at the instruction of his late wife.
He alleges Ms Anthony had failed to prove an earlier will made out in Sydney in 2014 which names the university as beneficiary. Mr Robinson also claims that a document subsequently deposited in the Supreme Court in July 2015 propounding to be this will is a ''forgery'', a ''composite, fabricated by a person or persons unknown''. Further, it was not Dr McCullough who had initialled certain clauses, documents claim.
The legal tussle came to light two years ago with the University of Oklahoma arguing that its foundation was the rightful beneficiary of Dr McCullough's estate.
In an amended statement of claim in 2016, Ms Anthony replaced the university as the plaintiff and has continued the claim, seeking orders that probate for the July 2014 will be granted.
Mr Robinson has instead asked the court to declare the January 2015 will to be Dr McCullough's final ''testamentary intentions''.
In dispute is Dr McCullough's estate including the author's royalties from her 25 books which will accumulate for 70 years after her death.
This includes sales from the global bestseller, The Thorn Birds as well as property on Norfolk Island but not the couple's home which is held in joint names with husband Ric Robinson and automatically transferred to him after her death.
Dr McCullough shot to fame for her second novel, The Thorn Birds (1977), the story of a doomed romance between a Catholic priest and a woman in the Australian outback.
It sold 33 million copies worldwide, smashed every publishing record at the time, and was turned into an award-winning television miniseries in 1983, starring Richard Chamberlain and Rachel Ward.
But she hated her newfound fame and moved to Norfolk Island where she met Robinson, 13 years her junior. She once described him as “a cross between Isaac Newton, a Samoan prince and a convict”.
It was her seven-novel series on the history of Rome which brought her to the attention of the University of Oklahoma. Dr McCullough was an honorary founding board member of the university's board of visitors at its College of International Studies.
Dr McCullough's British literary agent, Georgina Capel, estimates the value of revenue streams from the author's 25 books to be in the "low hundreds of thousands" and likely to dwindle as the years go on.
Ms Anthony claims there was no reason why Dr McCullough should change her mind to shun the American university.
Further, Dr McCullough did not receive independent legal advice and the making of the document was ''not of her own volition'', she claims.
Linda Morris is an arts and books writer for The Sydney Morning Herald.
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