Grace's Guide is the leading source of historical information on industry and manufacturing in Britain. This web publication contains 138,848 pages of information and 225,307 images on early companies, their products and the people who designed and built them.
of Canberra House, 313-319 Regent Street, London, W1. Telephone: Langham 3996-7-8. Cables: Halcyon, Wesdo, London".
1929 Advert for 5-valve Portable Wireless Receivers. Also as manufacturers of "De Luxe", Lightweight (Suit-case) and Cabinet Models. (Wireless Section - Stand No. MM.66) 
1934 Merchant H. C. Rawson was interested in Halcyon Radio Co which had recently introduced a new model and was also interested in television. John Ismay and Sons acquired a large interest in Rawsons.