of Euston Road, London, NW1.
of Vibrant Works, Treforest, Glamorgan.
WWII. During the war years they manufactured some fairly sensitive defence equipment for the British government.
1947 British Industries Fair Advert for "Yours in Harmony". Model D110/W and D111 Radios, and the Car Radio. Manufacturers of Radio Receivers, Car Radio Sets, Vibratorpacks. (Music and Radio Section - Olympia, Ground Floor, Stand No. C.1534) 
1953 Manufacturer of TV sets 
1956 Acquired R. M. Electric.
By 1958 was part of Francis Sumner (Holdings)
-  The Masteradio Website
Sources of Information
- 1947 British Industries Fair Advert 228; and p181
- Choosing your Television Set. Published by Freelance in 1953.
- The Times, Dec 31, 1962