The Brutal Reason Prince William Is 'Overjoyed' King Charles Is on Stand by to Back Cops in Andrew Windsor Epstein Probe

Prince William is said to be privately overjoyed by King Charles' unprecedented move to signal support for police investigating his brother Andrew Mountbatten-Windsor – a development insiders tell OK! strengthens William's hand to permanently exile the disgraced royal when he becomes king.

The Prince of Wales, 43, and his wife Kate Middleton, 44, recently issued a rare joint comment saying they were "deeply concerned by developments" surrounding Andrew, 65, in the wake of the release of the latest batch of files on Jeffrey Epstein, and that their "thoughts remain focused on the victims."

Their statement came as Buckingham Palace confirmed Charles, 77, is ready to support police if allegations against his brother escalate.

Thames Valley Police in London has confirmed it has widened its inquiry after complaints filed against Andrew by the anti-monarchy group Republic.

The force is assessing claims Andrew leaked confidential information to his pal Epstein while serving as the U.K.'s trade envoy, as well as allegations a second woman was trafficked to Britain for a sexual encounter with him in 2010. Andrew has consistently denied all wrongdoing and has not commented on the latest claims.

Buckingham Palace said: "The King has made clear, in words and through unprecedented actions, his profound concern at allegations which continue to come to light in respect of Mr Mountbatten-Windsor's conduct. While the specific claims in question are for Mr Mountbatten-Windsor to address, if we are approached by Thames Valley Police we stand ready to support them as you would expect."

Sources say the statement marks a decisive shift that has not gone unnoticed by William.

One senior palace insider told us: "William is absolutely overjoyed by this. He sees it as proof that the institution is finally willing to draw a hard line with Andrew, and that gives him confidence he will be able to act decisively when he becomes king."

Another source close to the Prince of Wales said: "William has always despised what Andrew represents and believes he has brought lasting shame on the monarchy. Seeing his father openly back the police tells William that there will be no consequences if he is even tougher in the future."

The new investigation centers on emails released by the U.S. Department of Justice that appear to show Andrew shared confidential reports and investment opportunities with Epstein between 2010 and 2011, after the serial abuser had been convicted of child s-- offenses.

One message on Christmas Eve allegedly looped Epstein into discussions about investment opportunities in Afghanistan.

Thames Valley Police is investigating potential misconduct in public office and a possible breach of the Official Secrets Act – offenses that carry severe penalties.

The force has said it is assessing the material in line with normal procedures and will seek legal advice on whether Andrew qualifies as a public officer under the law.

Former head of royal protection Dai Davies said he has been calling for Andrew to face prosecution for six years and urged police to act swiftly. Insiders insist William's reaction is deeply personal as well as strategic.

One source said: "William has wanted Andrew totally cast out of the royal family for years. He believes this moment proves the palace can survive it and that Andrew no longer has any protection."

Another palace aide added: "For William, this isn't about optics. It's about accountability. He feels vindicated seeing the palace take this stance and believes it clears the path for him to finish the job when his time comes."

On February 19, Andrew was taken into custody in the U.K. on suspicion of misconduct in public office after weeks of scrutiny over his ties to Epstein — whom Andrew allegedly forwarded confidential and sensitive information to while serving as a trade envoy for the U.K.

He was released that same day.