Diamond H came to life in the 1890's as the Hart Manufacturing Company designing and producing some of the first electric rotary switches -the Diamond H range.



Originally the company was based in London before moving 150 miles north to Norwich in the 1960's where part of the company remains to this day.



During that time, the product range changed and diversified many times as did the ownership.



Today the company is a division of the BI Group, itself a division of National ...