andMr. Deasy asked the Minister for Posts and Telegraphs whether reports that there is at present a common key for the vast majority of exchanges in the country are accurate; and whether he is satisfied that security is adequate in respect of line plant in view of the fact that connection point cabinets are often left unlocked.

It would not be in the public interest to disclose details of security arrangements at exchanges or other installations. Security arrangements are under continuous review in order to make improvements wherever these are found to be desirable and practicable.

Does the Minister accept that concern about high standards in the Department of Post and Telegraphs is not the concern merely of his side of the House and that this question has been motivated by persistent and consistent reports from responsible commentators that the plant to which the question refers is extremely vulnerable? Will the Minister investigate the matter raised in the question and, if necessary, carry out the necessary remedy?

The danger of a breach of secrecy as a result of a cabinet door being inadvertently left open or through vandalism is considered negligible. A detailed copy of the cable record and the possession of technical equipment would be absolutely necessary for this purpose and it is not available inside a cabinet at any given time. That report is without foundation.

In view of the Minister's categoric assurance that a breach of security would be virtually impossible in the circumstances, does he deny that it is possible to eavesdrop or tap telephone conversations with the use of equipment at a cabinet which has been broken into?

To the untrained mind it is absolutely impossible.

What about the trained mind?

It is not done in the cabinet. Surely a person with a trained mind would not stand in a public place and listen in on the line.

Is it possible to eavesdrop on a telephone conversation?

No, it is not.

The Minister has just suggested that it is possible.