"(4) A person cannot be compelled to give any evidence if his doing so would be prejudicial to the security of the United Kingdom. (5) A certificate signed by or on behalf of the Secretary of State or, where the court is in Scotland, the Lord Advocate to the effect that it would be so prejudicial for that person to do so is conclusive evidence of that fact." (6) A person cannot be compelled to give any evidence in his capacity as an officer or servant of the Crown."
"The 1975 Act and these Rules should be read and applied in close conjunction, for together they provide a comprehensive, self-contained code for obtaining evidence in England for use in proceedings in foreign courts." "
"The jurisdiction of English courts to order persons within its jurisdiction to provide oral or documentary evidence in aid of proceedings in foreign courts has always been exclusively statutory."
"Noting in the Act . . . prevents the Crown from facilitating the giving of evidence by its present or current officers . . . but the courts have no power to order anyone to give evidence in circumstances where Section 9(4) applies."
"It is true that in some of the cases the word "necessary" has been used, echoing or employing the language of Order 24, rule 13 of the Rules of the Supreme court. But, as Templeman LJ observed in British Steel Corporation v Granada Television Limited[1981] AC 1086 , 1132, "
"[The speeches in Norwich Pharmacal] make it clear that what is required is involvement or participation in the wrongdoing and that if there is the necessary involvement, it does not matter that the person from whom discovery is sought was innocent and in ignorance of the wrongdoing by the person whose identify it is hoped to establish."