Memorandum from Joseph P. Walshe to Eamon de Valera (Dublin)
(Secret)

Taoiseach, Minister for External Affairs.¹

Sir John Maffey came to see me at 10 o'clock this morning about what he described as a very urgent matter and in regard to which he asked for a decision by this evening.

He explained that the Radar posts on the Six Counties and Scottish coasts were proving ineffective owing to the damping of the signals by the Donegal mountains. His Government, therefore, earnestly requested us to allow them to establish a mobile and temporary post at Malin Head. The purpose of the post would be to pick up the radio pulsations from planes of the trans-Atlantic² airlines crossing the Atlantic to Scotland and to reflect them on to a post a Saligo Bay (Islay). It appears from what Sir John Maffey told me that it has become vitally important in recent times to know the exact situation of the planes crossing the Atlantic (which may be sending out by radio a special kind of information). The Radar gives the location of the plane and the Malin Head mobile post would merely 'reflect' to the Scottish post the directional impulses received.

This mobile post would be operated by fifteen civilians. The British would be very glad to allow some of our technicians to work with them and to learn how to operate a Radar post.

The Malin Head wireless station (Staff 11), which is operated for the British by us, has been transmitting signals by telegraph to Scotland giving information about submarine activities etc. The transmissions are frequently in code and the contents are, of course, not known to the operators. This station has been particularly valuable to the British because most of the Convoys had to go around by the Ulster coast and Malin Head would be the first and last station to pick up their signals and messages.

Valentia (Staff 12) served a similar purpose. The messages are transmitted by telegraph to London (Admiralty) and Devonport. The station would not have the same interest in relation to Radar because it is off the ferry route.³ Considerable additions to the apparatus were made about eight months ago without provoking comment.