Prince Andrew was absent at a formal dinner for NATO leaders at Buckingham Palace hosted by Queen Elizabeth II.
But the Duke of York remains the focus of renewed scrutiny as allegations of sexual misconduct received wide attention on British TV.
Andrew, who has stepped down from royal duties because of his involvement with sex offender Jeffrey Epstein, was the subject of a BBC documentary broadcast on Monday night in which he was accused of having sex with a 17-year-old American trafficked by Epstein.
President Donald Trump declined to offer an opinion when asked about the case earlier on Tuesday, saying only that he didn't know Andrew but that it was a "very tough story".
However, the alleged victim's father did weigh in, telling the ITV network he believes his daughter Virginia Roberts Giuffre's account is factual.
"I feel really sorry that all this happened. But it did happen, and Prince Andrew should pay for it," Sky Roberts said, adding that his daughter is "really brave to be going through all this and to come up against these powerful people".
The royal scandal, closely linked to the Epstein affair, was deepening as Trump and other dignitaries gathered in the splendour of Buckingham Palace to have drinks with Queen Elizabeth ahead of a NATO summit on Wednesday.
Andrew was not among those invited.
Giuffre, now 35, told the BBC in vivid detail how she was forced to have sex with Andrew in London in 2001 after a night on the town at the exclusive Tramp nightclub.
She said she had been recruited into Epstein's sex-trafficking network earlier when she was working as a locker room attendant at Trump's Mar-a-Lago club.
"This is not some sordid sex story. This is a story of being trafficked, this is a story of abuse and this is a story of your guys' royalty," Giuffre said, imploring the British public to back her in her quest for justice.
She says Andrew knows what happened and should accept responsibility.
Andrew has denied having sex with Giuffre and says he doesn't have any recollection of meeting her - despite a photo that appears to show him with his arm around her waist.
Andrew, 59, has apologised for his association with Epstein, who died in prison in August in what New York City officials ruled was a suicide. He was facing sex-trafficking charges after earlier serving time for other sex offences.
The disgraced prince says he is willing to cooperate with appropriate law enforcement inquiries if required to do so.
He also faces possible subpoenas from women who are suing Epstein's estate who believe Andrew may have valuable testimony about abuse they suffered.
The scandal is one of the worst to grip the royal household in recent decades and has severely tarnished Andrew's reputation.
US law enforcement agencies have not commented publicly on whether Andrew is being investigated for any possible wrongdoing.
Many of the court papers related to the Epstein case are still sealed and unavailable to the public.
British legal experts, meanwhile, are divided over whether Andrew enjoys immunity from prosecution as a senior British royal and the matter has not been tested in court.