The Queen showed her support for her son, the Duke of York, as he was plunged into a further round of damaging allegations following the apparent suicide of his former friend, the convicted paedophile Jeffrey Epstein.
She chose to sit next to the embattled Duke in a car, accompanied by his daughter Princess Beatrice, on the way to church at Balmoral on Sunday morning. All three could be seen smiling inside the vehicle.
The monarch's intervention came as prosecutors in New York said they were continuing to investigate a "conspiracy" of sex trafficking minors, and their attention turned to living associates of Epstein.
The Duke was last night braced for the release of further court documents.
Adam Citron, a former New York prosecutor, told The Telegraph the prosecutors would "absolutely" want to speak to the Duke and Ghislaine Maxwell, Epstein's British former girlfriend, as witnesses as they built up a picture of Epstein's world.
He said: "The case against Epstein is kaput. He's dead. But they're looking at a conspiracy, so you can still look at person X, Y, or Z. With all that's going on it would be political suicide for them not to speak to everyone. You've got all these people named. Of course they're going to investigate this whole thing.
"Being that you're talking about people in the UK, its pretty hard, but you can get a material witness order and the UK has a lot of treaties."
He added: "I don't think it will get that far. I'd assume Prince Andrew would want to cooperate if they ask. And I'm sure he'll have good lawyers, and they'll talk to the prosecutors back channel."
Virginia Giuffre, 36, who has claimed to have been Epstein's teen "sex slave," alleged in court documents that she had sex with the Duke when she was 17.
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.
The New York Post reported that Ms Maxwell was already "cooperating with federal authorities," but the report could not be verified.
Ms Maxwell's lawyers did not respond to a request for comment. Her current whereabouts is unknown.
None of the three lead prosecutors in the Epstein case returned requests for comment. Epstein's lawyer, Marc Fernich, declined to comment.
Geoffrey Berman, the US Attorney in Manhattan, said: "Our investigation of the conduct charged in the indictment, which included a conspiracy count, remains ongoing."
Mrs Giuffre told the the New York Times she was angry Epstein had been able to take his own life.
She said: "We've worked so hard to get here, and he stole that from us too."
Epstein died the day after the release of around 1,200 previously secret documents from a civil case in which Mrs Giuffre had sued Ms Maxwell for defamation.
In the court documents the Duke was alleged to have touched the breast of a young woman called Johanna Sjoberg, then 21, while at Epstein's home.
The documents were only the first tranche from the case, and there could be up to 10,000 more pages, expected in the next few weeks.
In them a host of high profile figures were named including former US senator George Mitchell, and the former New Mexico governor Bill Richardson, who have denied ever meeting Mrs Giuffre.
Meanwhile, the FBI has launched an investigation into how Epstein was allowed to die at the Metropolitan Correctional Center in Manhattan.
He had been placed on suicide watch following an apparent previous attempt on July 23, but then sent back to his cell, alone, a week later.
The two prison guards on duty when Epstein died were on overtime shifts.
According to standard practice inmates taken off suicide watch should have a cellmate.
But Epstein's cellmate, Nicholas Tartaglione, a former police officer charged with murder, was transferred, leaving Epstein alone in the cell.
New York City's chief medical examiner is confident Epstein's death was a suicide, but is awaiting more information before releasing her determination, the New York Times reported on Sunday, citing a city official.
An autopsy was performed earlier in the day on the disgraced financier, chief medical examiner Dr. Barbara Sampson said. A private pathologist observed the autopsy on behalf of Epstein's representatives, which she called "routine practice."
A determination on the cause of death "is pending further information at this time," Dr Sampson said in a statement.
Donald Trump fuelled conspiracy theories, suggesting that Bill Clinton had been to Epstein's "paedophile island," which Mr Clinton has denied.
The US president also retweeted a follower who wrote: "Jeffrey Epstein had information on Bill Clinton & now he’s dead. Retweet if you’re not Surprised."
A Clinton spokesman said: "Ridiculous, and of course not true - and Donald Trump knows it."
Rudi Giuliani, the president's lawyer, said: "Who was watching? What does camera show?... Follow the motives."
Mike Fisten, a private investigator who worked for years with Epstein's alleged victims, said: "There's a great case against the co-conspirators that helped Jeffrey out.
"I'm talking about the people who were bringing the girls to Jeffrey, the pimps, those are the people they're going to go after. I don't think Jeffrey being alive or dead is going to impact that much."
The Palace was approached for comment.