3Lawful interception without an interception warrant
(1)Conduct by any person consisting in the interception of a communication is authorised by this section if the communication is one which, or which that person has reasonable grounds for believing, is both—
(a)a communication sent by a person who has consented to the interception; and
(b)a communication the intended recipient of which has so consented.
(2)Conduct by any person consisting in the interception of a communication is authorised by this section if—
(a)the communication is one sent by, or intended for, a person who has consented to the interception; and
(b)surveillance by means of that interception has been authorised under Part II.
(3)Conduct consisting in the interception of a communication is authorised by this section if—
(a)it is conduct by or on behalf of a person who provides a postal service or a telecommunications service; and
(b)it takes place for purposes connected with the provision or operation of that service or with the enforcement, in relation to that service, of any enactment relating to the use of postal services or telecommunications services.
(4)Conduct by any person consisting in the interception of a communication in the course of its transmission by means of wireless telegraphy is authorised by this section if it takes place—
(a)with the authority of a designated person under section 5 of the [1949 c. 54.] Wireless Telegraphy Act 1949 (misleading messages and interception and disclosure of wireless telegraphy messages); and
(b)for purposes connected with anything falling within subsection (5).
(5)Each of the following falls within this subsection—
(a)the issue of licences under the [1949 c. 54.] Wireless Telegraphy Act 1949;
(b)the prevention or detection of anything which constitutes interference with wireless telegraphy; and
(c)the enforcement of any enactment contained in that Act or of any enactment not so contained that relates to such interference.