Prince Andrew is facing a private prosecution over allegations of sexual assault, corruption and misconduct in public office arising from the Virginia Giuffre scandal.
Campaign group Republic says it is taking the unprecedented step of instructing a law firm to investigate and, if appropriate, commence court proceedings against the disgraced royal.
The Metropolitan Police previously said it was looking into claims Andrew passed Ms Giuffre’s date of birth and social security number to his taxpayer-funded bodyguard in 2011 and asked him to dig up dirt on her.
Andrew has attempted to draw a line under years of controversy following his links to US paedophile financier Jeffrey Epstein.
The prince vehemently denies claims Ms Giuffre was forced to have sex with him three times after being trafficked by Epstein when she was aged 17.
He gave up his Duke of York title and other honours ahead of the publication of Giuffre’s posthumous memoirs.
Ms Giuffre’s brother and sister-in-law, Sky and Amanda Roberts, have called on the Independent Office for Police Conduct watchdog to review Scotland Yard’s decision not to continue its investigations into her allegations against King Charles’s brother.
Republic alleges there is a “powerful, principled argument for justice to be done for the victims of sexual abuse, and for those who corrupt public office to be held accountable”.
Graham Smith, chief executive of the campaign group, said: “If not us, then who?
“It’s a devastating indictment on the UK’s criminal justice system, police and politicians - not to mention the King and heir - that we must resort to a private prosecution.
“It should be a cause for concern that so many people believe - rightly in my view - that the royals are not treated equally in law. Equality in law is a basic tenet of democracy.
“I firmly believe there is strong enough evidence to justify a serious investigation. The authorities and politicians appear to want to look the other way, while minimising the accusations made against Andrew.
“The truth must prevail and justice must be seen to be done.”
Andrew’s accuser is said to have received up to £12 million in 2022 to settle her civil sexual assault case, despite the prince claiming never to have met her.
More recently, Andrew’s living arrangements have cause furore over his “peppercorn” rent at Royal Lodge, the 30-room mansion where he has lived for more than two decades.
He and his ex-wife Sarah Ferguson have agreed to leave the property in exchange for two separate residences, according to reports.
The BBC revealed that Andrew hosted Epstein, now convicted sex trafficker Ghislaine Maxwell and Harvey Weinstein at Royal Lodge ahead of his daughter Princess Beatrice’s masked ball 18th birthday celebrations at Windsor Castle in 2006.
On Monday, the King was heckled during an engagement in the Midlands.
Charles was a few metres away from a man in the crowd who asked a string of questions including “How long have you known about Andrew and Epstein?” during the visit to Lichfield Cathedral.
