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Rupert Murdoch presented an impression of almost otherworldly innocence in Court 73 of the Royal Courts of Justice: harmless, cuddly, a bit forgetful for sure, but nevertheless a man of definite integrity.

It was a charming event in its way. But watching this Oxford-educated showman, perhaps appearing for the final time on a public stage, it was easy to forget one important truth. The newspapers Mr Murdoch owns are under investigation for a number of crimes that include bribery, perversion of the course of justice, destruction of evidence, interception of emails, phone hacking and perjury.

No fewer than 16 of his editors or senior journalists, along with one chief executive and 10 reporters, have been arrested. There are three active police investigations, as a result...