Founded in the UK in 1964.
Electrosonic lighting desks and dimmers were sold in the UK by CCT Lighting.
In 1991, Electrosonic took over Celco.
Full and fascinating details about the company, products and history can be found in "Electrosonic: 50 Years on the Audio-Visual Front Line", published by the company in 2014.
Also, The First 50 Years Scrapbook can be downloaded from the Electrosonic website.