Another point of order altogether, Sir.

One of your prime concerns, Mr. Speaker, is to safeguard the rights and privileges of hon. Members. The matter that I wish to raise lies very much within your role as guardian of those rights.

I received yesterday a letter which has most disturbing implications. It was written by someone who was privy to the modernisation of the telephone network covering the Whitehall area. The key to that network was the CBX tandem which gave access to all telephone calls, internally and externally, and to some 70,000-plus telephone lines.

I have the letter here and I shall pass it to you, Mr. Speaker. You will, I believe, be already aware of the contents of a large part of that letter, as my hon. Friend the Member for Linlithgow (Mr. Dalyell) quoted it, at my request, yesterday.

The writer makes specific technical statements about the means of intercepting telephone calls made by hon. Members. He states the location of the buildings which house this massive equipment and explains the precise positioning of a particular room.

The letter says: Over a period of time, mostly outside normal working hours, a room immediately to the left at the bottom of the steps"— the writer has mentioned the building earlier— was installed with extensive and very sophisticated equipment. Later in the same letter, the writer says: It soon became accepted by all the Post Office now (BT staff) and the contracting engineers that the only possible purpose for which this equipment could be used was intercepting telephone calls. The writer claims that all the installations and equipment were mounted

a few weeks after MPs received push-button telephones instead of dial telephones. The writer appears to have no doubts about the purpose of that operation—the easy facility for eavesdropping on Member's calls both inside and outside the House.

I address this matter to you, Sir, in the eager expectation that you will require the matter to be investigated. If you argue that that responsibility lies in hands other than your own, I am sure that the House would urge you to advise them how the matter should be pursued because the implications are profoundly disturbing. Will you kindly, Sir, take this letter away with you and let the House have your views and advice tomorrow?