VP3MR 1935 British Guiana

Amateur radio station VP3BG also operated in the broadcast band where it called itself the Voice of Georgetown.
In 1938 after two years of operation it merged with VP3MR and the joint venture became the British Guiana United Broadcasting Company Ltd.
(source:  Jerome S. Berg's  Book The Early Shortwave Stations)

QSL, Info courtesy of Patrick Rigg