asked the Secretary of State for the Home Department, pursuant to his reply to the hon. Member for Leicester, South (Mr. Marshall) on 22 April, Official Report, c. 409, if he will set out the difference between surveillance and interception in relation to telephone tapping and bugging.

The interception of telephone communications covers what is said by both parties to the conversation. Surveillance equipment records or monitors what is said in a specific location and might thereby pick up what is said by one party to a telephone conversation.