"Thus, a conviction would be unsafe where the effect of an incorrect ruling of law on admitted facts was to leave an accused with no legal escape from a verdict of guilty on those facts. But a conviction would not normally be unsafe where an accused is influenced to change his plea to guilty because he recognises that, as a result of a ruling to admit strong evidence against him, his case on the facts is hopeless. A change of plea to guilty in such circumstances would normally be regarded as an acknowledgment of the truth of the facts constituting the offence charged. We qualify the above propositions with the word 'normally', because there remains the basic rule that the Court should quash as unsafe a conviction where the plea was mistaken or without intention to admit the guilt of the offence charged."
"1(1) It shall be an offence for a person intentionally and without lawful authority to intercept, at any place in the United Kingdom, any communication in the course of its transmission, by means of- (a) a public postal service; or (b) a public telecommunications system."
"For the purposes of this Act, but subject to the following provisions of this section, a person intercepts a communication in the course of its transmission by means of a telecommunication system if, and only if, he- (a) so modifies or interferes with the system, or its operation, (b) so monitors transmissions made by means of the system, or (c) so monitors transmissions made by wireless telegraphy to or from apparatus comprised in the system, as to make some or all of the contents of the communication available, while being transmitted, to a person other than the sender or intended recipient of the communication."
"Subject to section 18, no evidence shall be adduced, question asked, assertion or disclosure made or other thing done in, for the purposes of or in connection with any legal proceedings which (in any manner)- (a) discloses, in circumstances from which its origin in anything falling within subsection (2) may be inferred, any of the contents of an intercepted communication or any related communications data; or (b) tends (apart from any such disclosure) to suggest anything falling within subsection (2) has or may have occurred or be going to occur."
"The following fall within this subsection- (a) conduct by a person falling within subsection (3) that was or would be an offence under section 1(1) or (2) of this Act or undersection 1 of Interception of Communications Act 1985 ; (b) a breach by the Secretary of State of his duty under section 1(4) of this Act; (c) the issue of an interception warrant or of a warrant under theInterception of Communications Act 1985 ; (d) the making of an application by any person for an interception warrant, or for a warrant under that Act; (e) the imposition of any requirement of any person to provide assistance with giving effect to an interception warrant."
"Section 17(1)(a) shall not prohibit the disclosure of any of the contents of a communication if the interception of that communication was lawful by virtue of section 1(5)(c), 3 or 4."
"For the purposes of this Act a person is a covert human intelligence source if:- (a) he establishes or maintains a personal or other relationship with a person or the covert purpose of facilitating the doing of anything falling within paragraph (b) or (c). (b) he covertly uses such a relationship to obtain information or to provide access to any information to another person; or (c) he covertly discloses information obtained by the use of such a relationship, or as a consequence of the existence of such a relationship."
"Subject to subsection (6), surveillance is directed for the purposes of this Part if it is covert but not intrusive and is undertaken- (a) for the purposes of a specific investigation or a specific operation (b) in such a manner as is likely to result in the obtaining of private information about a person (whether or not one specifically identified for the purposes of the investigation or operation); and (c) otherwise than by way of an immediate response to events or circumstances the nature of which is such that it would not be reasonably practicable for an authorisation under this Part to be sought for the carrying out of the surveillance."
"authority is also given for the undercover officer to utilise tape recording equipment to effect independent corroboration"