The Duke of York's friendship with Jeffrey Epstein ultimately ended in acrimony after his wife called the financier a "paedophile" and refused to retract the statement.
Sarah, Duchess of York's public comment in 2011 enraged Epstein, who telephoned her publicist and threatened to sue her unless she took it back.
James Henderson, the publicist, told CNN he had a "deeply unpleasant" conversation with Epstein that left him hoping he never had to speak to him again.
The bitter fallout happened after the Duke and Epstein were photographed together walking in Central Park, New York in late 2010.
Publication of the picture in newspapers the following February led to criticism of the Duke over his decision to spend time with Epstein.
The businessman had, two years, been convicted of soliciting a minor for prostitution in Florida.
Amid the storm the Duke subsequently stepped down from his role as UK trade envoy.
Epstein was believed to have seen the Central Park photograph published on the front page of the New York Post, under the headline "Prince & Perv".
In March, 2011, the month after it was published, the Duchess then gave an interview in which she admitted to having received Â£15,000 from Epstein.
The money went to pay a debt to her former personal assistant, Johnny O'Sullivan.
She admitted the payment was arranged by the Duke's office and expressed contrition for a "gigantic error of judgment".
The Duchess said in the interview that Epstein had been "rightly jailed" in 2008.
She added: "I abhor paedophilia and any sexual abuse of children."
That comment reportedly led to Epstein's fury, and he called Mr Henderson, the publicist.
Mr Henderson told CNN: "It was so unpleasant that I was left slightly rattled and I saved his number so I'd never have to take a call from him again."
A letter from Epstein's lawyer then arrived with the Duchess, threatening legal action and demanding she retract the word "paedophilia".
Epstein even went as far as hiring a defamation lawyer in the UK, and proposed options were drawn up for a retraction of what the Duchess had said.
The Duchess stood her ground and refused to retract her statement.
Epstein's own lawyers then ended up suing him for $71,000 in unpaid bills, CNN reported.
The legal feud marked an end to the Duke and Duchess's relationship with Epstein.
The Duke has previously expressed regret at his decision to see Epstein in 2010, after his release from prison, calling his own actions a "mistake and an error".
Epstein took his own life in jail on August 10 in New York, where he was awaiting trial on new sex-trafficking charges.
Virginia Giuffre, 36, one of Epstein's alleged victims, has claimed she had sex with the Duke on three occasions when she was a teenager.
She has claimed that included an occasion in Florida she was 17, which would have been under the age of consent in the state.
All the allegations about the Duke were struck from the court record in 2015 after being described as "immaterial and impertinent" by a judge.
The Duke has always denied the allegations and any involvement.