"7. In order to track down Williams surveillance officers targeted his known associates and venues. One such associate was Andrea Piggott, a known drug user.
"(1) Subject to the following provisions of this section, and without prejudice to any other enactment, a constable may enter and search any premises for the purpose --
" False imprisonment -- Where the defendant justified the arrest of the plaintiff on the ground that the defendant had reasonable and probable cause for suspecting that a felony had been committed, and that the plaintiff had committed it, he was ordered to give particulars of the alleged felony and also of the reasonable and probable cause for suspicion, but not of the names of those who had given him information against the plaintiff( Green v Garbutt(1912) 28 TLR 575 , CA; and see Stapeley v Annetts[1970] 1 WLR 20 ;[1969] 3 All ER 1541 , CA)."
"The reasons why the application is made on this basis become evident from the material which has been placed before me and which I have read and considered. The upshot of the defendant's application is that, by reason of this material and the matters [of] fact which are dealt with in it, it requires that the court make an order on the basis of public interest immunity which would circumscribe the evidence which the defendant's officers would be obliged to deal with at the trial of this action. In short, the defendant seeks an order from me that at the time the defendant's officers entered the premises (that is 56 Pym House) they had reasonable grounds for believing that the person they were seeking, Joseph Williams, was on the premises, and a further order that at the trial of this matter the plaintiffs be prohibited from asking any questions of the defendant's witnesses, the answers to which may reveal the grounds for their belief that Joseph Williams was on the premises.
"Next as to procedure. In arresting, detaining or prosecuting a suspected felon a person is acting in furtherance of the administration of justice. It is a well-settled rule of procedure that the question whether in so doing he is acting reasonably is one to be decided by the judge. It may be that this rule reflects the judicial distrust of Jacobinism among juries at the formative period of this branch of English law; but it can at least be rationalised on the ground that a judge, by reason of his office and his experience, is better qualified than a juryman to determine what conduct is reasonable or unreasonable in furtherance of the administration of justice. In those days, however, the jury was the only tribunal which at common law was competent to determine disputed issues of fact. If there was conflicting evidence as to what had happened, that is, as to what the conduct of the defendant in fact was, the jury alone was competent to resolve the conflict. But when what had happened was established, whether by uncontradicted evidence or, in case of conflict, by the jury's finding of fact, it was for the judge to rule whether the defendant's conduct was reasonable or unreasonable. This is still the position today where an action for false imprisonment or malicious prosecution arising out of the arrest, detention or prosecution of a suspected felon is tried by judge and jury. It is for the judge to decide what facts given in evidence are relevant to the question of whether the defendant acted reasonably. It is thus for him to decide, in the event of a conflict of evidence, what finding of fact is relevant and requisite to enable him to decide that question. But a jury is entitled to base findings of fact only on the evidence called before it and, as in any other jury trial, it is for the judge in an action for false imprisonment or malicious prosecution to decide whether the evidence on a relevant matter does raise any issue of fact fit to be left to a jury. If there is no real conflict of evidence, there is no issue of fact calling for determination by the jury. This applies not only to issues of facts as to what happened, on which the judge has to base his determination whether the defendant acted reasonably, but also to the issue of fact whether the defendant acted honestly, which, if there is sufficient evidence to raise this issue, is one for the jury. (See Herniman v Smith[1938] AC 305 ). For the reasons already indicated, however, where there is reasonable and probable cause for an arrest or prosecution, the judge should not leave this issue to the jury except in the highly unlikely event that there is cogent positive evidence that, despite the actual existence of reasonable and probable cause, the defendant himself did not believe that it existed: see Glinski v McIver[1962] AC 726 ."
"As I have said in probably the majority of cases other than this, those grounds would have been very powerful arguments and would no doubt have caused the court to have considered very carefully before acceding to an application of the sort made in this case.
"Pleading the existence of facts giving rise to reasonable grounds for suspicion does not require informers to be identified, or documents or other information to which public interest immunity attaches to be disclosed. Debate about public interest immunity takes place in the context of argument on disclosure, where the issues are clear, the relevance of the withheld information can be ascertained, and the necessity for the documents or information to be disclosed can be judged in the light of available alternatives (including the administering of interrogatories): c.f. observations of Lord Woolf in Chief Constable of the West Midlands v Wiley[1995] 1 AC 274 at 288D-H."
" (i) surveillance by his police officers,