A letter from R.L. Smith-Rose, International Council of Scientific Unions, Inter-Union Committee for Frequency Allocations for Radio Astronomy and Space Science (U.R.S.I.-I.A.U.-C.O.S.P.A.R.), 21 Tumblewood Road, Banstead, Surrey, to Major Basil Binyon, O.B.E., M.A., M.I.E.E., 14 The Glen, Farnborough Park, Orpington, Kent, replying to his letter on the article he published.