In a statement released on Tuesday, the monarch confirmed he had been informed of the arrest and stressed the importance of allowing the legal process to proceed without interference.
“I have learned with the deepest concern the news about Andrew Mountbatten-Windsor and suspicion of misconduct in public office,” the King said. “What now follows is the full, fair and proper process by which this issue is investigated in the appropriate manner and by the appropriate authorities.”
The statement underlined the Palace’s stance of cooperation with law enforcement, with the King adding that the authorities “have our full and wholehearted support and co-operation”.
“Let me state clearly: the law must take its course,” he said.
King Charles also made clear that he would not comment further while the investigation is ongoing. “As this process continues, it would not be right for me to comment further on this matter,” the statement said. “Meanwhile, my family and I will continue in our duty and service to you all.”
No further details about the allegations or the investigation have been disclosed by police at this stage.

