Dr. Tom Frost, a public law expert from Loughborough University, suggested that Mountbatten-Windsor was probably interviewed by the police under caution.

“This could be the most significant arrest involving a Royal Family member since King Charles I faced charges of treason in January 1649,” said Frost.

He explained that misconduct in public office is considered a “very serious common law crime,” which could lead to a jury trial if charges are filed.

The crime carries a maximum penalty of life imprisonment.

Frost emphasized, “It’s important to note that this is still an early stage in the investigation.”

He added, “Under English law, everyone is presumed innocent until proven guilty in court. An arrest does not automatically result in charges being brought by the Crown Prosecution Service.”

Frost said an arrest does not necessarily mean Mountbatten-Windsor will be charged by the Crown Prosecution Service as the branch faces several processes and difficulties.

The Crown Prosecution Service has to assess whether to press charges under section four of the Code for Crown Prosecutors, also known as the full code test.

According to the code, the full code test should be applied only “when all outstanding reasonable lines of inquiry have been pursued”.

The full code test has two stages – the evidential stage and the public interest stage.

The Crown Prosecution Service must determine whether there is enough evidence to provide a realistic prospect of conviction and then whether that course of action is required in the public interest.

They will need to consider several factors, like the seriousness of the offence, the impact and harm to the victim, the impact on the community and whether sources of information require protection.

Frost said misconduct in public office is a difficult offence to prove for senior executives or senior political figures.

“There remains a high threshold before criminal proceedings can be brought for this offence,” he said.

Currently, the Public Office (Accountability) Bill is before parliament to replace the old common law offence with new offences to make it easier to hold senior executives and senior political figures to account.

Frost warned that if Mountbatten-Windsor is charged, it will be under the old common law.

Police have searched addresses in Norfolk and Berkshire.

Mountbatten-Windsor’s Sandringham home is in Norfolk and his former home at the Royal Lodge is in Berkshire, but police have not confirmed whether those were the locations searched.

His brother, King Charles III, has offered his “full and wholehearted support and co-operation” to the investigation.

“Let me state clearly: the law must take its course.”

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