Andrew Mountbatten-Windsor has been arrested on suspicion of misconduct in public office, Thames Valley Police have confirmed.
Police vehicles were spotted arriving at the Sandringham estate in Norfolk this morning, where Andrew Mountbatten-Windsor is currently residing on his 66th birthday.
Witnesses at the scene reported that those who arrived were wearing civilian clothing but "appeared to be police officers".
Thames Valley police, said in a statement confirming the arrest: "As part of the investigation, we have today (19/2) arrested a man in his sixties from Norfolk on suspicion of misconduct in public office and are carrying out searches at addresses in Berkshire and Norfolk.